Suspicious SysAidServer Child

Status: test
Severity: medium
Log source: category process_creation, product windows
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

Tactic	Techniques
Lateral Movement	`T1210` Exploitation of Remote Services

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

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

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ParentCommandLine`	match	`SysAidServer` corpus 2 (sigma 1, kusto 1)	`field:"ParentCommandLine" kind:match value:"SysAidServer"`
`ParentImage`	ends_with	`\java.exe` corpus 8 (sigma 8) `\javaw.exe` corpus 7 (sigma 7)	`field:"ParentImage" kind:ends_with`

Suspicious SysAidServer Child

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`