Detection rules › Sigma

Suspicious Environment Variable Has Been Registered

Severity
high
Author
Nasreddine Bencherchali (Nextron Systems)
Source
upstream

Detects the creation of user-specific or system-wide environment variables via the registry. Which contains suspicious commands and strings

Event coverage

ProviderEvent IDTitle
Sysmon13RegistryEvent (Value Set)

Stages and Predicates

Stage 1: all of selection_main

TargetObject|contains: '\Environment\'

Stage 2: all of selection_details

or:
Details: powershell
Details: pwsh
Details|contains: 'C:\Users\Public\'
Details|contains: JAG4AdgBvAGsAZQAtA
Details|contains: JbnZva2Ut
Details|contains: SQBuAHYAbwBrAGUALQ
Details|contains: SW52b2tlL
Details|contains: TVoAAAAAAAAAAAAA
Details|contains: TVpQAAIAAAAEAA8A
Details|contains: TVpTAQEAAAAEAAAA
Details|contains: TVqAAAEAAAAEABAA
Details|contains: TVqQAAMAAAAEAAAA
Details|contains: '\AppData\Local\Temp\'
Details|contains: kAbgB2AG8AawBlAC0A
Details|contains: ludm9rZS
Details|startswith: H4sIA
Details|startswith: Qzpc
Details|startswith: R2V0
Details|startswith: SQBFAF
Details|startswith: SQBuAH
Details|startswith: SUVY
Details|startswith: Y21k
Details|startswith: Yzpc
Details|startswith: aQBlA
Details|startswith: aWV4
Details|startswith: cABhAH
Details|startswith: cwBhA
Details|startswith: dXNpbm
Details|startswith: dgBhA
Details|startswith: dmFy

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
  • powershell
  • pwsh
Detailsmatch
  • C:\Users\Public\
  • JAG4AdgBvAGsAZQAtA
  • JbnZva2Ut
  • SQBuAHYAbwBrAGUALQ
  • SW52b2tlL
  • TVoAAAAAAAAAAAAA
  • TVpQAAIAAAAEAA8A
  • TVpTAQEAAAAEAAAA
  • TVqAAAEAAAAEABAA
  • TVqQAAMAAAAEAAAA
  • \AppData\Local\Temp\ corpus 9 (sigma 9)
  • kAbgB2AG8AawBlAC0A
  • ludm9rZS
Detailsstarts_with
  • H4sIA
  • Qzpc
  • R2V0
  • SQBFAF
  • SQBuAH
  • SUVY
  • Y21k
  • Yzpc
  • aQBlA
  • aWV4
  • cABhAH
  • cwBhA
  • dXNpbm
  • dgBhA
  • dmFy
TargetObjectmatch
  • \Environment\