detection.wiki

Detection rules › Sigma

PaperCut MF/NG Potential Exploitation

Status
test
Severity
high
Log source
product windows, category process_creation
Author
Nasreddine Bencherchali (Nextron Systems), Huntress DE&TH Team (idea)
Source
github.com/SigmaHQ/sigma

Detects suspicious child processes of "pc-app.exe". Which could indicate potential exploitation of PaperCut

MITRE ATT&CK coverage

TacticTechniques
ExecutionNo specific technique

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: PaperCut MF/NG Potential Exploitation
id: 0934ac71-a331-4e98-a034-d49c491fbbcb
status: test
description: Detects suspicious child processes of "pc-app.exe". Which could indicate potential exploitation of PaperCut
references:
    - https://www.huntress.com/blog/critical-vulnerabilities-in-papercut-print-management-software
    - https://github.com/huntresslabs/threat-intel/blob/3bad6b0fadfcca3ff5680923e74e39edd72f32da/2023/2023-04/20-PaperCut/win_susp_papercut_code_execution.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntress DE&TH Team (idea)
date: 2023-04-20
modified: 2023-04-25
tags:
    - attack.execution
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\pc-app.exe'
        Image|endswith:
            - '\bash.exe'
            - '\calc.exe'
            - '\certutil.exe'
            - '\cmd.exe'
            - '\csc.exe'
            - '\cscript.exe'
            - '\dllhost.exe'
            - '\mshta.exe'
            - '\msiexec.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\regsvr32.exe'
            - '\rundll32.exe'
            - '\scriptrunner.exe'
            - '\wmic.exe'
            - '\wscript.exe'
            - '\wsl.exe'
    condition: selection
falsepositives:
    - Legitimate administration activity
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    ParentImage|endswith: '\pc-app.exe'
    Image|endswith:
        - '\bash.exe'
        - '\calc.exe'
        - '\certutil.exe'
        - '\cmd.exe'
        - '\csc.exe'
        - '\cscript.exe'
        - '\dllhost.exe'
        - '\mshta.exe'
        - '\msiexec.exe'
        - '\powershell.exe'
        - '\pwsh.exe'
        - '\regsvr32.exe'
        - '\rundll32.exe'
        - '\scriptrunner.exe'
        - '\wmic.exe'
        - '\wscript.exe'
        - '\wsl.exe'

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
  • \bash.exe corpus 22 (sigma 22)
  • \calc.exe corpus 13 (sigma 13)
  • \certutil.exe corpus 43 (sigma 43)
  • \cmd.exe corpus 130 (sigma 130)
  • \csc.exe corpus 9 (sigma 9)
  • \cscript.exe corpus 73 (sigma 73)
  • \dllhost.exe corpus 11 (sigma 11)
  • \mshta.exe corpus 67 (sigma 67)
  • \msiexec.exe corpus 21 (sigma 21)
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
  • \regsvr32.exe corpus 65 (sigma 65)
  • \rundll32.exe corpus 95 (sigma 95)
  • \scriptrunner.exe corpus 12 (sigma 12)
  • \wmic.exe corpus 60 (sigma 60)
  • \wscript.exe corpus 75 (sigma 75)
  • \wsl.exe corpus 11 (sigma 11)
ParentImageends_with
  • \pc-app.exe