Detection rules › Sigma

Suspicious Binary Writes Via AnyDesk

Severity
high
Author
Nasreddine Bencherchali (Nextron Systems)
Source
upstream

Detects AnyDesk writing binary files to disk other than "gcapi.dll". According to RedCanary research it is highly abnormal for AnyDesk to write executable files to disk besides gcapi.dll, which is a legitimate DLL that is part of the Google Chrome web browser used to interact with the Google Cloud API. (See reference section for more details)

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1219.002 Remote Access Tools: Remote Desktop Software

Event coverage

ProviderEvent IDTitle
Sysmon11FileCreate

Stages and Predicates

Stage 1: selection

or:
Image|endswith: '\AnyDesk.exe'
Image|endswith: '\AnyDeskMSI.exe'
or:
TargetFilename|endswith: .dll
TargetFilename|endswith: .exe

Stage 2: not 1 of filter_dlls

TargetFilename|endswith: '\gcapi.dll'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Imageends_with
  • \AnyDesk.exe corpus 5 (sigma 5)
  • \AnyDeskMSI.exe corpus 4 (sigma 4)
TargetFilenameends_with
  • .dll corpus 21 (sigma 21)
  • .exe corpus 18 (sigma 18)
  • \gcapi.dll