Detection rules › Sigma

Potential Attachment Manager Settings Associations Tamper

Severity
high
Author
Nasreddine Bencherchali (Nextron Systems)
Source
upstream

Detects tampering with attachment manager settings policies associations to lower the default file type risks (See reference for more information)

Event coverage

ProviderEvent IDTitle
Sysmon13RegistryEvent (Value Set)

Stages and Predicates

Stage 1: selection_main

TargetObject|contains: '\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Associations\'

Stage 2: 1 of selection_value_default_file_type_rsik

Details: 'DWORD (0x00006152)'
TargetObject|endswith: '\DefaultFileTypeRisk'

Stage 3: 1 of selection_value_low_risk_filetypes

or:
Details|contains: '.bat;'
Details|contains: '.cmd;'
Details|contains: '.com;'
Details|contains: '.exe;'
Details|contains: '.htm;'
Details|contains: '.html;'
Details|contains: '.msi;'
Details|contains: '.rar;'
Details|contains: '.reg;'
Details|contains: '.zip;'
TargetObject|endswith: '\LowRiskFileTypes'

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
Detailseq
  • DWORD (0x00006152)
Detailsmatch
  • .bat;
  • .cmd;
  • .com;
  • .exe;
  • .htm;
  • .html;
  • .msi;
  • .rar;
  • .reg;
  • .zip;
TargetObjectends_with
  • \DefaultFileTypeRisk
  • \LowRiskFileTypes
TargetObjectmatch
  • \SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Associations\