SolarWinds Serv-U FTP Server 15.2.1 Path Traversal

`Title: Path traversal  
  
  
  
Product: SolarWinds Serv-U FTP Server  
  
  
  
Vendor Homepage: https://www.solarwinds.com/  
  
  
  
Vulnerable Version: 15.2.1 and lower  
  
  
  
Fixed Version: 15.2.2  
  
  
  
CVE Number: CVE-2020-27994  
  
  
  
Author: Jack Misiura from The Missing Link   
  
  
  
Website: https://www.themissinglink.com.au  
  
  
  
Timeline:  
  
  
  
2020-10-28 Disclosed to Vendor  
  
2021-01-21 Vendor releases patched version  
  
2021-08-02 Publication  
  
  
  
1. Vulnerability Description  
  
  
  
SolarWinds Serv-U File Server through 15.2.1 does not correctly validate path information, allowing the disclosure of files and directories outside of the user's home directory via a specially crafted GET request.  
  
  
  
  
  
2. PoC  
  
  
  
On a vulnerable Serv-U installation issue the following GET request to get a listing of files and directories above the user's directory:  
  
  
  
https://<serv-u host>/Web Client/?Command=List&dir=\..\*.*  
  
  
  
The user *MUST* be locked to their directory, and only access granted must be the said directory. Directory listing must be enabled. If any of the above is not present, the exploit will not work.  
  
  
  
3. Solution  
  
  
  
The vendor provides an updated version (15.2.2) which should be installed immediately.  
  
  
  
4. Advisory URL  
  
  
  
https://www.themissinglink.com.au/security-advisories  
  
  
  
  
  
  
  
  
Jack Misiura​  
  
  
Application Security Consultant  
  
  
  
  
a  
  
  
  
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Artarmon  
  
  
NSW  
  
  
2064  
  
  
  
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1300 865 865  
  
  
  
os  
  
  
+61 2 8436 8585  
  
  
  
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