Detection rules › Sigma

HackTool - CobaltStrike BOF Injection Pattern

Status
test
Severity
high
Log source
product windows, category process_access
Author
Christian Burkard (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects a typical pattern of a CobaltStrike BOF which inject into other processes

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1106 Native API
Defense ImpairmentT1685 Disable or Modify Tools

Event coverage

ProviderEventTitle
SysmonEvent ID 10ProcessAccess

Rule body yaml

title: HackTool - CobaltStrike BOF Injection Pattern
id: 09706624-b7f6-455d-9d02-adee024cee1d
status: test
description: Detects a typical pattern of a CobaltStrike BOF which inject into other processes
references:
    - https://github.com/boku7/injectAmsiBypass
    - https://github.com/boku7/spawn
author: Christian Burkard (Nextron Systems)
date: 2021-08-04
modified: 2023-11-28
tags:
    - attack.execution
    - attack.defense-impairment
    - attack.t1106
    - attack.t1685
logsource:
    category: process_access
    product: windows
detection:
    selection:
        CallTrace|re: '^C:\\Windows\\SYSTEM32\\ntdll\.dll\+[a-z0-9]{4,6}\|C:\\Windows\\System32\\KERNELBASE\.dll\+[a-z0-9]{4,6}\|UNKNOWN\([A-Z0-9]{16}\)$'
        GrantedAccess:
            - '0x1028'
            - '0x1fffff'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    CallTrace|re: '^C:\\Windows\\SYSTEM32\\ntdll\.dll\+[a-z0-9]{4,6}\|C:\\Windows\\System32\\KERNELBASE\.dll\+[a-z0-9]{4,6}\|UNKNOWN\([A-Z0-9]{16}\)$'
    GrantedAccess:
        - '0x1028'
        - '0x1fffff'

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
CallTraceregex_match
  • ^C:\Windows\SYSTEM32\ntdll.dll+[a-z0-9]{4,6}|C:\Windows\System32\KERNELBASE.dll+[a-z0-9]{4,6}|UNKNOWN([A-Z0-9]{16})$
GrantedAccesseq
  • 0x1028
  • 0x1fffff corpus 9 (sigma 7, splunk 1, kusto 1)