Cloud forensics: Why enabling Microsoft Azure Key Vault logs matters
Co-authors - Christoph Dreymann - Abul Azed - Shiva P. Introduction As organizations increase their cloud adoption to accelerate AI readiness, Microsoft Incident Response has observed the rise of cloud-based threats as attackers seek to access sensitive data and exploit vulnerabilities stemming from misconfigurations often caused by rapid deployments. In this blog series, Cloud Forensics, we share insights from our frontline investigations to help organizations better understand the evolving threat landscape and implement effective strategies to protect their cloud environments. This blog post explores the importance of enabling and analyzing Microsoft Azure Key Vault logs in the context of security investigations. Microsoft Incident Response has observed cases where threat actors specifically targeted Key Vault instances. In the absence of proper logging, conducting thorough investigations becomes significantly more difficult. Given the highly sensitive nature of the data stored in Key Vault, it is a common target for malicious activity. Moreover, attacks against this service often leave minimal forensic evidence when verbose logging is not properly configured during deployment. We will walk through realistic attack scenarios, illustrating how these threats manifest in log data and highlighting the value of enabling comprehensive logging for detection. Key Vault Key Vault is a cloud service designed for secure storage and retrieval of critical secrets such as passwords or database connection strings. In addition to secrets, it can store other information such as certificates and cryptographic keys. To ensure effective monitoring of activities performed on a specific instance of Key Vault, it is essential to enable logging. When audit logging is not enabled, and there is a security breach, it is often difficult to ascertain which secrets were accessed without comprehensive logs. Given the importance of the assets protected by Key Vault, it is imperative to enable logging during the deployment phase. How to enable logging Logging must be enabled separately for each Key Vault instance either in the Microsoft Azure portal, Azure command-line interface (CLI) or Azure PowerShell. How to enable logging can be found here. Alternatively, it can be configured within the default log analytics workspace as an Azure Policy. How to use this method can be found here. By directing these logs to a Log Analytics workspace, storage account, or event hub for security information and event management (SIEM) ingestion, they can be utilized for threat detection and, more importantly, to ascertain when an identity was compromised and which type of sensitive information was accessed through that compromised identity. Without this logging, it is difficult to confirm whether any material has been accessed and therefore may need to be treated as compromised. NOTE: There are no license requirements to enable logging within Key Vault, but Log Analytics charges based on ingestion and retention for usage of that service (Pricing - Azure Monitor | Microsoft Azure) Next, we will review the structure of the Audit Logs originating from the Key Vault instance. These logs are located in the AzureDiagnostics table. Interesting fields Below is a good starting query to begin investigating activity performed against a Key Vault instance: AzureDiagnostics | where ResourceType == 'VAULTS' The "operationName" field is of particular significance as it indicates the type of operation that took place. An overview of Key Vault operations can be found here. The "Identity" field includes details about the identity responsible for an activity, such as the object identifier and UPN. Lastly, the “callerIpAddress” shows which IP address the requests originate from. The table below displays the fields highlighted and used in this article. Field name Description time Date and time in UTC. resourceId The Key Vault resource ID uniquely identifies a Key Vault in Azure and is used for various operations and configurations. callerIpAddress IP address of the client that made the request. Identity The identity structure includes various information. The identity can be a "user," a "service principal," or a combination such as "user+appId" when the request originates from an Azure PowerShell cmdlet. Different fields are available based on this. The most important ones are: identity_claim_upn_s: Specifies the upn of a user identity_claim_appid_g: Contains the appid identity_claim_idtyp_s: Shows what type of identity was used OperationName The name of the operation, for instance SecretGet Resource Key Vault Name ResourceType Always “VAULTS” requestUri_s The requested Key Vault API call contains valuable information. Each API call has its own structure. For example, the SecretGet request URI is: {vaultBaseUrl}/secrets/{secret-name}/{secret-version}?api-version=7.4. For more information, please see: https://learn.microsoft.com/en-us/rest/api/keyvault/?view=rest-keyvault-keys-7.4 httpStatusCode_d Indicates if an API call was successful A complete list of fields can be found here. To analyze further, we need to understand how a threat actor can access a Key Vault by examining the Access Policy and Azure role-based access control (RBAC) permission model used within it. Access Policy permission model vs Azure RBAC The Access Policy Permission Model operates solely on the data plane, specifically for Azure Key Vault. The data plane is the access pathway for creating, reading, updating, and deleting assets stored within the Key Vault instance. Via a Key Vault Access Policy, you can assign individual permissions and grant access to security principals such as users, groups, service principals, and managed identities, at the Key Vault scope with appropriate Control Plane privileges. This model provides flexibility by granting access to keys, secrets, and certificates through specific permissions. However, it is considered a legacy authorization system native to Key Vault. Note: The Access Policies permission model has privilege escalation risks and lacks Privileged Identity Management support. It is not recommended for critical data and workloads. On the other hand, Azure RBAC operates on both Azure's control and data planes. It is built on Azure Resource Manager, allowing for centralized access management of Azure resources. Azure RBAC controls access by creating role assignments, which consist of a security principal, a role definition (predefined set of permissions), and a scope (a group of resources or an individual resource). RBAC offers several advantages, including a unified access control model for Azure resources and integration with Privileged Identity Management. More information regarding Azure RBAC can be found here. Now, let’s dive into how threat actors can gain access to a Key Vault. How a threat actor can access a Key Vault When a Key Vault is configured with Access Policy permission, privileges can be escalated under certain circumstances. If a threat actor gains access to an identity that has been assigned the Key Vault Contributor Azure RBAC role, Contributor role or any role that includes 'Microsoft.KeyVault/vaults/write' permissions, they can escalate their privileges by setting a Key Vault access policy to grant themselves data plane access, which in turn allows them to read and modify the contents of the Key Vault. Modifying the permission model requires 'Microsoft.Authorization/roleAssignments/write' permission, which is included in the Owner and User Access Administrator roles. Therefore, a threat actor cannot change the permission model without one of these roles. Any change to the authorization mode will be logged in the Activity Logs of the subscription, as shown in the figure below: If a new Access Policy is added, it will generate the following entry within the Azure Activity Log: When Azure RBAC is the permissions model for a Key Vault, a threat actor must identify an identity within the Entra ID tenant that has access to sensitive information or one capable of assigning such permissions. Information about Azure RBAC roles for Key Vault access, specifically those who can access Secrets, can be found here. A threat actor that has compromised an identity with an Owner role is authorized to manage all operations, including resources, access policies, and roles within the Key Vault. In contrast, a threat actor with a Contributor role can handle management operations but does not have access to keys, secrets, or certificates. This restriction applies when the RBAC model is used within a Key Vault. The following section will examine the typical actions performed by a threat actor after gathering permissions. Attack scenario Let's review the common steps threat actors take after gaining initial access to Microsoft Azure. We will focus on the Azure Resource Manager layer (responsible for deploying and managing resources), as its Azure RBAC or Access Policy permissions determine what a threat actor can view or access within Key Vault(s). Enumeration Initially, threat actors aim to understand the existing organizations' attack surface. As such, all Azure resources will be enumerated. The scope of this enumeration is determined by the access rights held by the compromised identity. If the compromised identity possesses access comparable to that of a reader or a Key Vault reader at the subscription level (reader permission is included in a variety of Azure RBAC roles), it can read numerous resource groups. Conversely, if the identity's access is restricted, it may only view a specific subset of resources, such as Key Vaults. Consequently, a threat actor can only interact with those Key Vaults that are visible to them. Once the Key Vault name is identified, a threat actor can interact with the Key Vault, and these interactions will be logged within the AzureDiagnostics table. List secrets / List certificates Operation With the Key Vault Name, a threat actor could list secrets or certificates (Operation: SecretList and CertificateList) if they have the appropriate rights (while this is not the final secret, it indicates under which name the secret or certificate can be retrieved). If not, access attempts would appear as unsuccessful operations within the httpStatusCode_d field, aiding in detecting such activities. Therefore, a high number of unauthorized operations on different Key Vaults could be an indicator of suspicious activity as shown in the figure below: The following query assists in detecting potential unauthorized access patterns. Query: AzureDiagnostics | where ResourceType == 'VAULTS' and OperationName != "Authentication" | summarize MinTime = min(TimeGenerated), MaxTime = max(TimeGenerated), OperationCount=count(), UnauthorizedAccess=countif(httpStatusCode_d >= 400), OperationNames = make_set(OperationName), make_set_if(httpStatusCode_d, httpStatusCode_d >= 400), VaultName=make_set(Resource) by CallerIPAddress | where OperationNames has_any ("SecretList", "CertificateList") and UnauthorizedAccess > 0 When a threat actor uses a browser for interaction, the VaultGet operation is usually the first action when accessing a Key Vault. This operation can also be performed via direct API calls and is not limited to browser use. High-Privileged account store Next, we assume a successful attempt to access a global admin password for Entra ID. Analyzing Secret retrieval When an individual has the identifier of a Key Vault and has SecretList and SecretGet access rights, they can list all the secrets stored within the Key Vault (OperationName SecretList). In this instance, this secret includes a password. Upon identifying the secret name, the secret value can be retrieved (OperationName SecretGet). The image below illustrates what appears in the AzureDiagnostics table. The HTTP status code indicates that these actions were successful. The requestUri contains the name of the secret, such as "BreakGlassAccountTenant" for the SecretGet operation. With this information, one can ascertain what secret has been accessed. The requestUri_s format for the SecretGet operation is as follows: {vaultBaseUrl}/secrets/{secret-name}/{secret-version}?api-version=7.4 When the browser accesses the Key Vault service through the Azure portal, additional API calls are often involved due to the various views within the Key Vault services in Azure. The figure below illustrates this process. When someone accesses a specific Key Vault via a browser, the VaultGet operation is followed by SecretList. To further distinguish actions, SecretListVersion will also be used, as the Key Vault service shows different versions of a Secret, which may indicate direct browser usage. The final SecretGet Operation retrieves the actual secret. When using the Key Vault, SecretList operations can be accompanied by SecretGet operations. This is less common for emergency accounts since these accounts are infrequently used. Setting up alerts when certain secrets are retrieved can assist in identifying unusual activity. Entra ID Application certificate store In addition to storing secrets, certificates that provide access to Entra ID applications can also be managed within a Key Vault. When creating an Entra ID application with a certificate for authentication, you can automatically store that certificate within a Key Vault of your choice. Access to such certificates could allow a threat actor to leverage the access rights of the associated Entra ID application and gain access to Entra ID. For instance, if the Entra ID application possesses significant permissions, the extracted certificate could be utilized to exercise those permissions. Various Entra ID roles can be leveraged to elevate privileges; however, for this scenario, we assume the targeted application holds the "RoleManagement.ReadWrite.Directory" permission. Consequently, the Entra ID application would have the capability to assign the Global Admin role to a user account controlled by the threat actor. We have also described this scenario here. Analyzing Certificate retrieval The figure below outlines the procedure for a threat actor to download a certificate and its private key using the Key Vault API. First, the CertificateList operation displays all certificates within a Key Vault. Next, the SecretGet operation retrieves a specific certificate along with its private key (the SecretGet operation is required to obtain both the certificate and its private key). When a threat actor uses the browser through the Azure portal, the sequence of actions should resemble those in the figure below: When a Certificate object is selected within a specific Key Vault view, all certificates are displayed (Operation: CertificateList). Upon selecting a particular certificate in this view, the operations CertificateGet and CertificateListVersions are executed. Subsequently, when a specific version is selected, the CertificateGet operation will be invoked again. When "Download in PFX/PEM format" is selected, the SecretGet Operation downloads the Certificate and private key within the Browser. With the downloaded certificate, the threat actor can sign in as the Entra application and utilize the assigned permissions. Key Vault summary Detecting misuse of a Key Vault instance can be challenging, as operations like SecretGet can be legitimate. A threat actor might easily masquerade their activities among legitimate users. Nevertheless, unusual attributes, such as IP addresses or peculiar access patterns, could serve as indicators. If an identity is known to be compromised and has utilized Key Vaults, the Key Vault logs must be checked to determine what has been accessed to respond appropriately. Coming up next Stay tuned for the next blog in the Cloud Forensics series. If you haven’t already, please read our previous blog about hunting with Microsoft Graph activity logs.Total Identity Compromise: Microsoft Incident Response lessons on securing Active Directory
Total Identity Compromise: Microsoft Incident Response lessons on securing Active Directory When Microsoft Incident Response (formerly DART/CRSP) is engaged during an incident, almost all environments include an on-premises Active Directory component. In most of these engagements, threat actors have taken full control of Active Directory –i.e., total domain compromise. Total domain compromise often starts with the compromise of a regular non-privileged user rather than a domain admin. Threat actors can use that account to discover misconfiguration and attack paths in Active Directory that lead to full domain control. Oftentimes, threat actors leverage freely available tools such as AdFind, AD Explorer, or BloodHound to find attack paths through Active Directory environments. After total domain compromise, restoring trust back into Active Directory can take significant time and investment. To aid in our investigations, Microsoft Incident Response leverages a custom-built Active Directory enumeration tool to retrieve metadata about users, groups, permissions, group policies and more. Microsoft Incident Response uses this data to not only aid in the investigation, but also to shape attacker eviction and compromise recovery plans and to provide best practice recommendations on taking back and maintaining positive identity control. In addition to the Microsoft Incident Response custom tool, there are other tools, such as Defender for Identity, and open-source tools such as BloodHound and PingCastle, that you can use to secure Active Directory in your own environment. Across all industry verticals, Microsoft Incident Response often finds similar issues within Active Directory environments. In this blog, we will be highlighting some of the most common issues seen in on-premises Active Directory environments and provide guidance on how to secure those weaknesses. These include: Initial Access – Weak password policies, excessive privilege and poor credential hygiene, insecure account configuration Credential Access – Privileged credential exposure, Kerberoasting, insecure delegation configuration, Local Administrator Password Solution (LAPS) misconfiguration, excessive privilege via built-in groups Privilege Escalation – Access control list (ACL) abuse, escalation via Exchange permissions, Group Policy abuse, insecure trust configuration, compromise of other Tier 0 assets Initial Access Weak Password Policies It is not uncommon for Microsoft Incident Response to engage with customers where accounts have weak or easy to guess credentials, including those of privileged users such as Domain Admins. Simple password spray attacks can lead to the compromise of such accounts. If these standard user accounts are provided VPN or remote access without multi-factor authentication, the risk is increased: threat actors can connect to the VPN via devices in their control and begin reconnaissance of the environment remotely. From here, a threat actor can then attempt to escalate to Domain Admin privileges via weaknesses in Active Directory. Recommendation Where possible, Microsoft Incident Response recommends deploying passwordless authentication technology, such as Windows Hello for Business (which uses biometrics such as facial recognition or fingerprints) or FIDO2 security keys. Fully deploying passwordless authentication allows you to disallow password authentication, which eliminates password-based attack vectors (such as password sprays and phishing) for those users. If you are not yet ready to begin deploying passwordless solutions, you can increase the strength of your on-premises password policy through group policy and fine-grained password policies. Current guidance recommends longer (14 or more characters) but less complex passwords (no special characters or similar required), with users having to change them much less frequently. This discourages users from cycling through easy-to-guess passwords to satisfy complexity and rotation requirements, such as changing their password from ‘Monday10’ to ‘Monday11’. If you are licensed for Azure Active Directory P1 or higher, you can also deploy Azure Active Directory Password Protection, which can disallow your users from using easy to guess passwords even in on-premises Active Directory. You can also ban custom words unique to your business, such as the name of your company or the city in which you operate. For both passwordless and stronger password policies, if you work in a complex environment where the rollout of those solutions may take some time, start by targeting your Domain Admins and other privileged users. Your Tier 0 accounts can, and should, be held to a higher security standard. Excessive Privilege and Poor Credential Hygiene One of the most common issues found in Active Directory is accounts, particularly service accounts, being assigned too much privilege. In Microsoft Incident Response engagements, it is not uncommon to find multiple service accounts and named user accounts to be granted Domain Admin privileges. Additionally, service accounts used for applications or scripts are often granted local administrative access over all workstations and servers. Though this is an easy way to allow a product or script to function, these accounts then become a weak point in your security. Service accounts are attractive targets because the passwords are rarely rotated. Security controls for them are often weaker, and they can’t be protected by MFA. Furthermore, the passwords for these accounts are often stored in clear text, whether that be sent in email, saved to text files on devices, or used in clear text in command line arguments. The combination of many Domain Admin accounts and poor technical controls over those accounts increase the risk for credential theft. This excessive privilege also extends to too many users having local administrative rights on their own devices. If a compromised user does not have local administrative rights on their device, it is harder for a threat actor to continue to move laterally in the environment from that device. Recommendation There is no specific guidance on how many Domain Admin accounts should exist in each environment, as the requirements for privileged accounts will be unique for each environment. With that said, any requests to have additional Domain Admins should be scrutinized closely, with the preference always being to grant a lower level of privilege, particularly to service accounts. Even though adding service accounts to Domain Admins is an easy way to ensure an application works, most of these accounts can be assigned much less privilege and still function correctly. They can also often be granted access to only a subset of devices rather than all workstations and servers. If you don’t have strong controls to govern secure credential practice for your most important accounts, then the more Domain Admin level accounts you add, the more risk you incur. For service accounts, investigate whether Group Managed Service Accounts (gMSA), which can provide automatic password management, would be suitable for the workload. Insecure Account Configuration In Active Directory, misconfiguration can be a reason the security of individual user accounts is weaker than it could be. Some of the settings to scrutinize for proper configuration include: Do not require Kerberos pre-authentication. Store password using reversible encryption. Password not required. Password stored with weak encryption. Enabling any of these settings drastically reduces the security of an account. An adversary can enumerate a directory with relative ease to find any accounts that have these flags. The credentials for these accounts may then be easier for a threat actor to retrieve. Recommendation Defender for Identity, via the Secure Score portal, provides an excellent summary of these risky account flags. For each configuration item, it lists which accounts are affected and how to remediate the issue. Other tooling such as BloodHound or PingCastle can also flag these account issues. Credential Access Privileged Credential Exposure During cyber-attacks, adversaries often seek to obtain privileged credentials. These credentials are viewed as ‘crown jewels’ because they allow threat actors to complete their objectives. Once privileged credentials are obtained, they can be used to: Add additional persistence mechanisms, such as scheduled tasks, installing services, or creating additional user accounts. Disable or bypass endpoint antivirus or other security controls. Deploy malware or ransomware. Exfiltrate sensitive data. As administrators log on to devices directly or connect to devices remotely to complete their day-to-day work, they may leave behind privileged credentials. Threat actors can leverage tools such as Mimikatz or secretsdump (part of the Impacket framework) to retrieve those credentials. As privileged users log on to more and more machines, attackers have additional opportunities to locate and extract those credentials. For example, if members of the Domain Admins group regularly log on to end user workstations to troubleshoot issues, then Domain Admin credentials may be exposed on each device, increasing a threat actor’s chances of locating and extracting them. To help customers understand this privileged credential spread, Microsoft Incident Response collects logon telemetry from the event logs on devices, signals from Microsoft Defender for Endpoint, or both. From that data, a map is created of Tier 0 accounts, such as Domain Admins, logging onto devices that are not considered Tier 0, such as member servers and workstations. Figure 1: Map of Domain Admin login paths to non-Tier 0 servers. In this visual, the green circles represent Domain Admins. The red dotted lines represent RDP logons to devices, while the black dotted lines represent network logons. In this example, we can see two domain admins that have logged onto three different servers. Should a threat actor compromise one of these three servers, there is potential for theft of a Domain Admin level credential. The larger the environment, the more this issue becomes apparent. If we add additional admins and other non-Tier 0 devices, we can see the immediate impact on our footprint. Figure 2: Map of Domain Admin login paths to non-Tier 0 servers and other devices. With additional Domain Admins and those admins logging onto other non-tier 0 devices, credential exposure has increased significantly. The goal of these diagrams is to help customers visualize where privileged credentials are being left on their network and to start thinking from the mindset of a threat actor. In large and complex Active Directory environments, these diagrams can become immense, and the number of endpoints climbs into the thousands. Recommendation Microsoft’s solution to reduce privileged credential exposure is to implement the enterprise access model. This administration model seeks to reduce the spread of privileged credentials by restricting the devices that Domain Admins (and similar accounts) can log on to. In large and complex environments, it is safe to assume that some users and devices will be compromised. Your most privileged accounts should only access Tier 0 assets from hardened devices, known as privileged access workstations (PAWs). Using least-privileged access is a key part of Zero Trust principals. By reducing the opportunity to extract privileged credentials, we reduce the impact of compromise on a single device or user. Deploying the enterprise access model is a journey, and every organization is at a different stage of that journey. Regardless of your current posture, you can always reduce privilege credential spread, both through technical controls and changes to the way staff work. This table in the Microsoft Learn documentation lists various logon types and whether credentials are left on the destination device. When administering remote systems, Microsoft Incident Response recommends using methods that do not leave credentials behind wherever possible. Defender for Identity also maps these lateral movement paths, showing paths where compromise of a regular user can lead to domain compromise. These are integrated directly within user and computer objects in the Microsoft 365 Defender portal. Figure 3: Defender for Identity page for mapping a user’s lateral movement paths. The highest risk users and computers are also shown in the Secure Score portal, allowing you to remediate objects most at risk. Kerberoasting Kerberoasting is a technique used by threat actors to crack the passwords of accounts, generally service accounts, that have service principal names (SPNs) associated with them. If a regular user in Active Directory is compromised, they can request a ticket (which includes the hashed password) via tools such as Rubeus for any account with an SPN configured. The threat actor can then extract this hash from memory and attempt to crack the password offline. If they can crack the password, they can then authenticate as and assume the privileges of that service account. It is also not uncommon for Microsoft Incident Response to detect SPNs registered to privileged admin accounts or service accounts that have been added to privileged groups. Often these SPNs are configured for testing and then never removed, leaving them vulnerable to Kerberoasting. Recommendation Microsoft Incident Response recommends that you review all accounts configured with SPNs to ensure they are still required. For those that are actively in use, ensure the passwords associated for those accounts are extremely complex and rotated where practical. Defender for Identity includes logic to detect Kerberoasting activity in your environment. By taking signals from your domain controllers, Defender for Identity can help detect users enumerating your domain looking for Kerberoast-able accounts or attempts to actively exploit those accounts. Insecure Delegation Configuration Unconstrained Kerberos delegation provides the ability for an entity to impersonate other users. This helps with authentication through multi-tier applications. For example, a web server running IIS may have delegation configured to access an SQL server, which stores the data for the web site. When you log onto the web server, the web server then uses delegation to authenticate on behalf of you to SQL. In doing this, the user’s Kerberos Ticket Granting Ticket (TGT) is stored in memory on the web server. If a threat actor compromises that web server, they could retrieve those tickets and impersonate any users that had logged on. If a Domain Admin happened to log on, then the threat actor would have access to a Domain Admin TGT and could assume full control of Active Directory. Recommendation Review all the users and devices that are enabled for delegation. These are available in the Defender for Identity section of Secure Score. If delegation is required it should be restricted to only the required services, not fully unconstrained. Administrative accounts should never be enabled for delegation. You can prevent these privileged accounts from being targeted by enabling the ‘Account is sensitive and cannot be delegated’ flag on them. You can optionally add these accounts to the ‘Protected Users’ group. This group provides protections over and above just preventing delegation and makes them even more secure; however, it may cause operational issues, so it is worth testing in your environment. Local Administrator Password Solution (LAPS) Microsoft Incident Response often encounters situations where LAPS has not been deployed to an environment. LAPS is the Microsoft solution to automatically manage the password for the built-in Administrator account on Windows devices. When machines are built or imaged, they often have the same password for the built-in Administrator account. If this is never changed, a single password can give local administrative rights to all machines and may provide opportunities for lateral movement. LAPS solves this problem by ensuring each device has a unique local administrator password and rotates it regularly. Additionally, even in cases where LAPS has been deployed, sometimes it has not been fully operationalized by the business. As a result, despite LAPS managing the local administrator account on these devices, there are still user groups that have local administrative rights over all the workstations or all the servers, or both. These groups can contain numerous users, generally belonging to the service desk or other operations staff. These operational staff then use their own accounts to administer those devices, rather than the LAPS credentials. IT configurations can also exist where a secondary, non-LAPS managed account still exists with an easy to guess password, defeating the benefit gained by deploying LAPS. As noted earlier, groups with broad administrative access give threat actors additional opportunity to compromise privileged credentials. Should an endpoint where one of these accounts has logged onto become compromised, a threat actor could have credentials to compromise all the devices in the network. Recommendation It is important to not only deploy LAPS to endpoints, but to ensure that IT standard operating procedures are updated to ensure LAPS is used. This allows companies to remove privilege from administrative accounts and reduce credential theft risk across the business Additionally, it is crucial to understand which users can retrieve the LAPS password for use, since the ability to retrieve this password grants local administrative access to that device. The ability to read the LAPS password is controlled via the ‘ms-Mcs-AdmPwd’ attribute and should be audited to ensure access is only granted to users that require it. Excessive Privilege via Built-In Groups During incident response, companies often have alerting and monitoring in place for changes to groups like Domain and Enterprise Admins. These groups are widely known to hold the highest level of privilege in Active Directory. However, there are other privileged built-in groups that are attractive to threat actors and are often not held to the same level of scrutiny. Groups such as Account and Server Operators have wide ranging privilege over your Active Directory. For example, by default Server Operators can log on to Domain Controllers, restart services, backup and restore files, and more. Recommendation It is recommended that, where possible, privileged built-in groups not contain any users. Instead, the appropriate privilege should be granted specifically to users that require it. Additionally, Microsoft Incident Response recommends reviewing the current membership of those groups and adding additional alerting to changes to them in the same way you would alert on Domain or Enterprise admin changes. Privilege Escalation Access Control List Abuse Access Control Lists (ACL) misconfiguration is one of the most common issues Microsoft Incident Response finds in Active Directory environments. Active Directory ACLs are exceptionally granular, complex, and easy to configure incorrectly. It is easy to reduce the security posture of your Active Directory environment without having any operational impact on your users. As ACLs are configured in your environment through business-as-usual activities, attack paths start to form. These attack paths create an escalation path from a low privileged user to total domain control. A threat actor can take advantage of the paths created by the combination of excessive privilege and scope on ACLs. A threat actor can take advantage of the paths created by the combination of excessive privilege and scope on ACLs. Two common ACLs that Microsoft Incident Response sees regularly in Active Directory are: GenericAll – this privilege is the same as Full Control access. If a user was compromised and that user had GenericAll over a highly privileged group, then the threat actor could add additional members to that group. WriteDacl – this privilege allows manipulation of the ACL on an object. With this privilege a threat actor can change the ACL on an object such as a group. If a user was compromised and that user had WriteDacl over a highly privileged group, the threat actor could add a new ACL to that group. That new ACL could then give them access to add additional members to the group, such as themselves. These permissions are often set at the top of the Active Directory hierarchy. They are also often applied to users and groups that do not require those permissions, effectively granting those group members full domain control. The members of these groups are very rarely secured in the same way that Domain and Enterprise Admins are. In addition, Microsoft Incident Response often detects insecure ACLs on the AdminSdHolder object, which is responsible for managing permissions on protected users and groups. If an adversary can manipulate the ACL on AdminSdHolder, it will be propagated on to those protected users and groups when the SDProp process runs. The adversary will then have rights to change membership of protected groups such as Domain Admins, allowing them to add themselves. The documentation for BloodHound describes these and several other ACL ‘edges’ that can be abused for privilege escalation. Recommendation Microsoft Incident Response recommends auditing permissions through your Active Directory environment using tools such as Defender for Identity and running sanctioned audits of attack paths using BloodHound and remediating paths that can lead to domain compromise. Escalation via Exchange Permissions Prior to the use of corporate cloud email services such as Office 365, customers ran their own on-premises Exchange environments. Many customers still maintain a complete on-premises Exchange environment. On-premises Exchange and Active Directory have always been tied closely together, with Exchange maintaining high privilege through Active Directory. Even in environments that have migrated user mailboxes to Office 365, an on-premises Exchange footprint often remains. It may exist to manage users not yet migrated, for legacy applications that are not able to integrate with Office 365, or to service non-internet connected workloads. These on-premises Exchange environments often retain high privilege through Active Directory, and groups such as ‘Exchange Trusted Subsystem’ and ‘Exchange Servers’ can have a direct path to total domain control. On-premises Exchange is also often internet-facing to allow users to access resources such as Outlook Web Access. Like any internet facing service, this increases the surface area for attack. If a threat actor can obtain SYSTEM privilege on an Exchange server and Exchange still retains excessive permissions in Active Directory, then it can lead to complete domain compromise. Recommendation It is possible to decouple the privilege held by Exchange in Active Directory by deploying the split permissions model for Exchange. By deploying this model, permissions for Active Directory and Exchange are separated. After deploying the Exchange split permissions model, there are operational changes required by staff who administer both Exchange and Active Directory. If you don’t want to deploy the entire split permissions model, you can still reduce the permissions Exchange has in Active Directory by implementing the changes in the following Microsoft guidance. If you have completely migrated to Office 365 but maintain on-premises Exchange servers for ease of management, you may now be able to turn off those on-premises servers. Group Policy ACL Abuse Group Policy is often a tool used by threat actors to establish persistence (via the creation of scheduled tasks), create additional accounts, or deploy malware. It is also used as a ransomware deployment mechanism. If a threat actor has not yet compromised a Domain Admin, they may have been able to compromise an account that maintains permissions over Group Policy Objects. For instance, the ability to create, update, or even link policies may have been delegated to other groups. If an existing Group Policy is configured to run a startup script, a threat actor can change the path of that script to then have it execute a malicious payload. If a group policy exists to disable endpoint security tooling as an exemption, a threat actor could leverage the permissions to link policy by applying that policy to all devices in the environment. This would not require the threat actor to update the policy, just change the scope of it. Additionally, regular users can be given additional privileges via User Rights Assignments. These privileges are often not required by the users and are granted accidentally. Recommendation The ability to manipulate Group Policy is a highly privileged action and users and groups with delegated responsibility to manage it should be held to the same standards as Domain Admins or similar. Ensure that permissions to create, update, and link group policies are in line with least privilege principles. In large and complex environments, the number of Group Policies in use can be overwhelming and it is not clear what policies apply to which users and devices. Using tools such as Resultant Set of Policy (RSoP), you can model your Group Policy objects to see the overall effect on your users and devices. Insecure Trust Configuration SID history is a capability in Active Directory to aid in domain migration. It allows Domain Admins to simplify migration by applying the SID history (in simple terms, a list of permissions) from the old account to the new account. This helps the user retain access to resources once they are migrated. An adversary can target this capability by inserting the SIDs of groups such as Domain Admins into the SID history of an account in the trusted forest and using that account to take control of the trusting forest. This can be especially relevant during mergers and acquisitions, where trusts between Active Directory environments are configured to allow migrations. Recommendation Active Directory trusts should only be configured when absolutely required. If they are part of an acquisition or migration, then they should be decommissioned once migration is complete. For trusts that need to remain for operational reasons, SID filtering and Selective Authentication should be configured to reduce the attack path from other domains and forests. Compromise of other Tier 0 assets Historically, domain controllers have been at the center of Tier 0 infrastructure. While that is still true, Tier 0 has now expanded to include several interconnected systems. As ways of working have evolved, so has the underlying technology required to drive modern identity systems. In line with that, your Tier 0 footprint has also evolved and may now include systems such as: Active Directory Federation Services Azure Active Directory Connect Active Directory Certificate Services It also includes any other services or infrastructure, including 3 rd party providers, that form part of your identity trust chain, such as privileged access management and identity governance systems. Figure 4: Example of how Tier 0 assets connect to an identity trust chain. It is important that all systems that form part of your end-to-end identity chain are included in Tier 0, and the security controls you apply to domain controllers also apply to these systems. Due to the interconnected nature of these systems, compromise of any one of them could lead to complete domain compromise. Only Tier 0 accounts should retain local administrative privileges over these systems and, where practical, access to them should be via a privileged access workstation. Summary In large and complex environments, Microsoft Incident Response often sees combinations of the above issues that reduce identity security posture significantly. These misconfigurations allow threat actors to elevate from a single non privileged user all the way to your crown jewel Domain Admin accounts. Figure 5: Kill chain showing how domain compromise can start from a single compromised user. For example, in the above kill chain, the first user was compromised due to a weak password policy. Through the initial poor password policy, additional bad credential hygiene, and ACL misconfiguration, the domain was compromised. When you multiply all the combinations of user accounts, group access, and permissions in Active Directory, many paths can exist to Domain Admin. Attacks on Active Directory are ever evolving, and this blog covers only some of the more common issues Microsoft Incident Response observes in customer environments. Ultimately, any changes made to Active Directory can either increase or decrease the risk that a threat actor can take control of your environment. To ensure that risk is consistently decreasing, Microsoft Incident Response recommends a constant cycle of the below: Reduce Privilege – assign all access according to the principle of least privilege. Additionally, deploy the enterprise access model to reduce privileged credential exposure. Combined, these will reduce the likelihood that a single device or user compromise leads to total domain compromise. Audit Current Posture – use tools such as Defender for Identity and sanctioned use of BloodHound and PingCastle to audit your current Active Directory security posture and remediate the issues both surfaced through those tools and described in this blog. Monitor Changes – monitor for changes to your Active Directory environment that can reduce your security posture or expose additional attack paths to domain compromise. Actively Detect – alert on potential signs of compromise using Defender for Identity or custom detection rules. A message that Microsoft Incident Response often leaves customers with is that securing Active Directory requires continued governance. You can’t ‘deploy’ Active Directory security and never have to look at it again. Active Directory security is about constant improvement and ensuring those misconfigurations and attack paths are mitigated before an adversary finds them.From prevention to recovery: Microsoft Unified’s holistic cybersecurity approach
Author - Paul Saigar The latest Microsoft Digital Defense Report states that 80 percent of organizations have attack paths that expose critical assets. Furthermore, Microsoft has observed a 2.75x increase year over year in ransomware attacks among our customers. Cyber-enabled financial fraud is also rising globally. According to our report, the daily traffic volume for Tech scams – a type of fraud that tricks users by impersonating legitimate services or using fake tech support and ads – has skyrocketed by 400 per cent since 2022. This is a stark contrast to the 180 per cent increase in malware and 30 per cent in phishing over the same period. Microsoft is committed to helping organizations meet this growing challenge with a suite of integrated technologies and services designed to let customers operate with confidence. Microsoft Unified services and the role of Microsoft IR (incident response) Microsoft IR is backed by our elite Detection and Response Team (DART) and is an essential component of Microsoft’s overall cybersecurity offering for customers. This team consists of highly skilled cybersecurity professionals with extensive backgrounds in threat hunting and intelligence, digital forensics and tactical recovery, with experience in handling both proactive and reactive incident response. DART’s approach is twofold: it focuses on immediate incident response and pre-emptive measures to prevent security breaches before they occur. Proactive measures: Microsoft IR, backed by DART, conducts comprehensive assessments of organizational security infrastructures, seeking out vulnerabilities and potential threats. By evaluating the security readiness of identity and endpoint management systems, our DART experts provide customized recommendations to enhance security measures. Reactive strategies: In the event of a cybersecurity incident, DART’s response is swift and effective. The team engages directly with the threat, isolating affected systems to prevent further damage while conducting a thorough analysis to identify the source and nature of the attack. Recovery processes are implemented to restore integrity to the systems and data affected. Throughout the cybersecurity response, our DART experts provide continuous support and updates to ensure stakeholders are informed and prepared for necessary actions. This comprehensive approach is supported by Microsoft’s vast threat intelligence, which analyses 78 trillion security signals daily, and state-of-the-art technologies. That includes proprietary tools and widely recognized solutions such as the Microsoft Defender suite and Microsoft Sentinel. The depth of expertise within DART ensures it is equipped to manage complex cyber threats efficiently, making the team a trusted and vital component of our cybersecurity offering. Expanding Microsoft Unified’s cybersecurity offering Recognizing the critical need for rapid and robust incident management, Microsoft IR, our Cybersecurity Incident Response (CIR) service, is being offered through Microsoft Unified. This offering provides access to our global network of cybersecurity experts, who offer onsite and remote support, ensuring comprehensive coverage and swift action. Our CIR offering also integrates seamlessly with our broader Microsoft Unified framework. Initial contact: Our Unified team serves as the first line of contact for triage and validation of suspected cybersecurity incidents, providing timely and efficient incident isolation and remediation. Escalated response: When an incident escalates beyond initial containment, our CIR team takes comprehensive control, ensuring extensive investigation, containment, and recovery. The suite of services that make up CIR includes prioritized response times, with DART experts available within two hours to address security incidents. It also includes comprehensive services ranging from threat investigation, digital forensics, and malware analysis to complete recovery and remediation efforts. Organizations can also access proactive compromise assessments that delve deep into their environments to unearth vulnerabilities, potential indicators of compromise, potential attack vectors, and inform roadmaps to bolster their defenses. These services are complemented by regular threat intelligence briefings tailored to specific industry and geographical threats to keep organizations informed and prepared. Engage with Microsoft Unified Microsoft Unified provides an indispensable resource for organizations aiming to enhance their cybersecurity readiness. We integrate proactive assessments with rapid, effective incident response capabilities to equip businesses with the necessary tools and expertise to confront and mitigate cyber threats. To learn more about how Microsoft can help protect your organization from cyber threats, visit our Microsoft Unified page. To learn more about Microsoft IR (incident response), please visit Microsoft Incident Response page.
