Potential Exploitation Attempt Of Undocumented WindowsServer RCE

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

Detects potential exploitation attempt of undocumented Windows Server Pre Auth Remote Code Execution (RCE)

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1190` Exploit Public-Facing Application

Telemetry coverage

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

Rule body

title: Potential Exploitation Attempt Of Undocumented WindowsServer RCE
id: 6d5b8176-d87d-4402-8af4-53aee9db7b5d
status: test
description: Detects potential exploitation attempt of undocumented Windows Server Pre Auth Remote Code Execution (RCE)
references:
    - https://github.com/SigmaHQ/sigma/pull/3946
    - https://twitter.com/hackerfantastic/status/1616455335203438592?s=20
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali
date: 2023-01-21
tags:
    - attack.initial-access
    - attack.t1190
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\svchost.exe'
        Image|endswith: '\svchost.exe'
        ParentCommandLine|contains: '-k DHCPServer'
        CommandLine|contains: '-k DHCPServer'
        User|contains: # Covers many language settings for Network Service. Please expand.
            - 'NETWORK SERVICE'
            - 'NETZWERKDIENST'
            - 'SERVIZIO DI RETE'
            - 'SERVICIO DE RED'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ParentImage|endswith: '\svchost.exe'
    Image|endswith: '\svchost.exe'
    ParentCommandLine|contains: '-k DHCPServer'
    CommandLine|contains: '-k DHCPServer'
    User|contains:
        - 'NETWORK SERVICE'
        - 'NETZWERKDIENST'
        - 'SERVIZIO DI RETE'
        - 'SERVICIO DE RED'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`-k DHCPServer`	`field:"CommandLine" kind:match value:"-k DHCPServer"`
`Image`	ends_with	`\svchost.exe` corpus 23 (sigma 22, kusto 1)	`field:"Image" kind:ends_with value:"\svchost.exe"`
`ParentCommandLine`	match	`-k DHCPServer`	`field:"ParentCommandLine" kind:match value:"-k DHCPServer"`
`ParentImage`	ends_with	`\svchost.exe` corpus 15 (sigma 14, kusto 1)	`field:"ParentImage" kind:ends_with value:"\svchost.exe"`
`User`	match	`NETWORK SERVICE` `NETZWERKDIENST` `SERVICIO DE RED` `SERVIZIO DI RETE`	`field:"user" kind:match`

Potential Exploitation Attempt Of Undocumented WindowsServer RCE

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`