Question Malware modify, delete, corrupt files

Not every type of malicious software is designed to damage files, but many have the capability to modify, delete, or corrupt data if that’s how they are coded.

Main types of malicious software that can affect files:

• Ransomware: encrypts user files and removes the originals, demanding payment to restore access.
• Wipers: erase or overwrite data completely, often used in destructive attacks.
• File infectors (viruses): attach malicious code to programs or documents, which can corrupt files.
• Trojans or backdoors: provide remote access to the system, allowing attackers to alter or delete files.
• Downloaders or droppers: install additional malware that might later damage data.
• Network worms: spread automatically and sometimes include destructive components.
• Information stealers: focus on gathering data or credentials but can lead to other types of infections.

About the examples you mentioned:

• QtWebKit4.dll flagged as Trojan:Win32/Wacatac.C!ml — usually a generic trojan that can download or execute other components.
• Caller.exe flagged as Trojan.DownLoader47.36298 — a downloader used to fetch and run additional payloads.
• Caller.exe flagged as TrojanPSW.Rhadamanthys — a password-stealing trojan designed to collect user credentials.

These samples themselves are not destructive by design, but they can introduce or trigger other malware that is.

Recommended steps:

1. Disconnect the affected device from the network.
2. Run a complete scan with Microsoft Defender or another trusted endpoint security tool.
3. Remove any detected items and restart the system.
4. Change all passwords used on that device.
5. If this is part of a work environment, review security logs and session tokens to rule out persistence.
6. Restore files only from backups created before the infection, after confirming they are clean.

These actions help ensure the threat is fully contained and prevent future data loss or unauthorized access.