MediumSigmaHQ frack113

Suspicious Appended Extension

Detects file renames where the target filename uses an uncommon double extension. Could indicate potential ransomware activity renaming files and adding a custom extension to the encrypted files, such as…

Description

Detects file renames where the target filename uses an uncommon double extension. Could indicate potential ransomware activity renaming files and adding a custom extension to the encrypted files, such as ".jpg.crypted", ".docx.locky", etc.

Detection logic

Detection requirements

Platform: ESXi IaaS Linux macOS Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
Log source product: windows
Log source category: file_rename

Known benign triggers

Backup software

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
app.any.run/tasks/d66ead5a-faf4-4437-93aa-65785afaf9e5/	Sandbox submission	Only this detection cites it
blog.cyble.com/2022/08/10/onyx-ransomware-renames-its-leak-site-to-vsop/	Unclassified	Only this detection cites it

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Detection rules

Suspicious Appended Extension

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules