Detection rules › Sigma

Suspicious Child Process Of BgInfo.EXE

Severity
high
Author
Nasreddine Bencherchali (Nextron Systems)
Source
upstream

Detects suspicious child processes of "BgInfo.exe" which could be a sign of potential abuse of the binary to proxy execution via external VBScript

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.005 Command and Scripting Interpreter: Visual Basic
Defense EvasionT1202 Indirect Command Execution, T1218 System Binary Proxy Execution

Event coverage

ProviderEvent IDTitle
Sysmon1Process creation
Security-Auditing4688A new process has been created.

Stages and Predicates

Stage 1: all of selection_parent

or:
ParentImage|endswith: '\bginfo.exe'
ParentImage|endswith: '\bginfo64.exe'

Stage 2: all of selection_child

or:
Image|endswith: '\calc.exe'
Image|endswith: '\cmd.exe'
Image|endswith: '\cscript.exe'
Image|endswith: '\mshta.exe'
Image|endswith: '\notepad.exe'
Image|endswith: '\powershell.exe'
Image|endswith: '\pwsh.exe'
Image|endswith: '\wscript.exe'
Image|contains: ':\PerfLogs\'
Image|contains: ':\Temp\'
Image|contains: ':\Users\Public\'
Image|contains: ':\Windows\Temp\'
Image|contains: '\AppData\Local\'
Image|contains: '\AppData\Roaming\'

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
  • \calc.exe corpus 13 (sigma 13)
  • \cmd.exe corpus 92 (sigma 92)
  • \cscript.exe corpus 64 (sigma 64)
  • \mshta.exe corpus 57 (sigma 57)
  • \notepad.exe corpus 11 (sigma 11)
  • \powershell.exe corpus 143 (sigma 143)
  • \pwsh.exe corpus 140 (sigma 140)
  • \wscript.exe corpus 64 (sigma 64)
Imagematch
  • :\PerfLogs\ corpus 4 (sigma 4)
  • :\Temp\ corpus 12 (sigma 12)
  • :\Users\Public\ corpus 14 (sigma 14)
  • :\Windows\Temp\ corpus 9 (sigma 9)
  • \AppData\Local\
  • \AppData\Roaming\ corpus 2 (sigma 2)
ParentImageends_with
  • \bginfo.exe corpus 2 (sigma 2)
  • \bginfo64.exe corpus 2 (sigma 2)