Detection rules › Sigma

Assembly DLL Creation Via AspNetCompiler

Severity
medium
Author
Nasreddine Bencherchali (Nextron Systems)
Source
upstream

Detects the creation of new DLL assembly files by "aspnet_compiler.exe", which could be a sign of "aspnet_compiler" abuse to proxy execution through a build provider.

Event coverage

ProviderEvent IDTitle
Sysmon11FileCreate

Stages and Predicates

Stage 1: selection

Image|endswith: '\aspnet_compiler.exe'
TargetFilename|contains: .dll
TargetFilename|contains: '\Temporary ASP.NET Files\'
TargetFilename|contains: '\assembly\tmp\'

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
  • \aspnet_compiler.exe corpus 3 (sigma 3)
TargetFilenamematch
  • .dll
  • \Temporary ASP.NET Files\
  • \assembly\tmp\