Detection rules › Splunk
Git Clone Repository (PowerShell)
Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency. Recent vulnerabilities identified would allow adversaries remote code execution after cloning a repo. GIT-LFS CVE-2020-27955
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | T1105 Ingress Tool Transfer |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Rule body yaml
id: '6100.6572'
title: Git Clone Repository
description: Git is a free and open source distributed version control system designed
to handle everything from small to very large projects with speed and efficiency.
Recent vulnerabilities identified would allow adversaries remote code execution
after cloning a repo. GIT-LFS CVE-2020-27955
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR
TERM(<EventID>4104<)) (TERM(git) OR TERM(GH)) TERM(clone) | table _time, host, user,
signature_id, process, process_* | bin span=1s | stats values(*) as * by _time,
host '
techniques:
- command-and-control:ingress tool transfer
technique_id:
- T1105
data_category:
- PowerShell logs
- Process command-line parameters
references:
- https://exploitbox.io/vuln/Git-Git-LFS-RCE-Exploit-CVE-2020-27955.html
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR TERM(<EventID>4104<)) (TERM(git) OR TERM(GH)) TERM(clone)
Stage 2: table
| table _time, host, user, signature_id, process, process_*
Stage 3: bucket
| bin span=1s
Stage 4: stats
| stats values(*) as * by _time, host
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.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | TERM |
| 1 | "<EventID>4104<" |
| 1 | TERM |
| 1 | git |
| 1 | TERM |
| 1 | GH |
| 1 | TERM |
| 1 | clone |