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Detection rules › Sigma

HackTool - CobaltStrike BOF Injection Pattern

Status
test
Severity
high
Log source
category process_access, product windows
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
Execution
Defense Impairment

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 10: ProcessAccess

Rule body

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

These rows show field, operator, and value matches.

FieldKindValuesSearch
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})$
field:"CallTrace" kind:regex_match value:"^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)
field:"GrantedAccess" kind:eq