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Detection rules › Sigma

Suspicious SysAidServer Child

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
Florian Roth (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects suspicious child processes of SysAidServer (as seen in MERCURY threat actor intrusions)

MITRE ATT&CK coverage

TacticTechniques
Lateral MovementT1210 Exploitation of Remote Services

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Suspicious SysAidServer Child
id: 60bfeac3-0d35-4302-8efb-1dd16f715bc6
status: test
description: Detects suspicious child processes of SysAidServer (as seen in MERCURY threat actor intrusions)
references:
    - https://www.microsoft.com/security/blog/2022/08/25/mercury-leveraging-log4j-2-vulnerabilities-in-unpatched-systems-to-target-israeli-organizations/
author: Florian Roth (Nextron Systems)
date: 2022-08-26
tags:
    - attack.lateral-movement
    - attack.t1210
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\java.exe'
            - '\javaw.exe'
        ParentCommandLine|contains: 'SysAidServer'
    condition: selection
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ParentImage|endswith:
        - '\java.exe'
        - '\javaw.exe'
    ParentCommandLine|contains: 'SysAidServer'

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
ParentCommandLinematch
  • SysAidServer
ParentImageends_with
  • \java.exe corpus 8 (sigma 8)
  • \javaw.exe corpus 7 (sigma 7)