Detection rules › Sigma

Suspicious Access to Sensitive File Extensions

Severity
medium
Author
Samir Bousseaden
Source
upstream

Detects known sensitive file extensions accessed on a network share

MITRE ATT&CK coverage

TacticTechniques
CollectionT1039 Data from Network Shared Drive

Event coverage

ProviderEvent IDTitle
Security-Auditing5145A network share object was checked to see whether client can be granted desired access.

Stages and Predicates

Stage 1: selection

or:
RelativeTargetName|endswith: .bak
RelativeTargetName|endswith: .dmp
RelativeTargetName|endswith: .edb
RelativeTargetName|endswith: .kirbi
RelativeTargetName|endswith: .msg
RelativeTargetName|endswith: .nsf
RelativeTargetName|endswith: .nst
RelativeTargetName|endswith: .oab
RelativeTargetName|endswith: .ost
RelativeTargetName|endswith: .pst
RelativeTargetName|endswith: .rdp

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
RelativeTargetNameends_with
  • .bak
  • .dmp
  • .edb
  • .kirbi
  • .msg
  • .nsf
  • .nst
  • .oab
  • .ost
  • .pst
  • .rdp

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.