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Directory Traversal Vulnerability in SolarWinds Serv-U

CVE-2024-28995 proof-of-concept

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Directory Traversal Vulnerability in SolarWinds Serv-U


CVE-2024-28995 is a critical directory traversal vulnerability in SolarWinds Serv-U, affecting versions 15.4 and earlier across multiple platforms including Windows and Linux. This vulnerability enables unauthenticated attackers to read arbitrary files on the system, potentially leading to sensitive data exposure. SolarWinds has released a hotfix (15.4.2 Hotfix 2) to mitigate this issue, and immediate updates are recommended.

Affected Versions

  • Serv-U FTP Server 15.4

  • Serv-U Gateway 15.4

  • Serv-U MFT Server 15.4

  • Serv-U File Server 15.4

Technical Details

The vulnerability stems from insufficient validation of user input in the file transfer functionality of Serv-U. Specifically, the parameters InternalDir and InternalFile are retrieved and passed to a vulnerable function without proper sanitization, allowing directory traversal attacks.

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Proof of Concept (PoC)

The vulnerability can be exploited by crafting an HTTP request that includes manipulated file paths, using traversal sequences to access files outside the intended directories.

  1. Identifying the Vulnerable Endpoint: In almost all uses of the vulnerable function, the InternalDir and InternalFile parameters are passed to it.

  2. Crafting the Malicious Request: By manipulating these parameters, an attacker can construct a path that includes traversal sequences to access arbitrary files.

Example curl command to test the vulnerability:

  1. Demonstrating File Access: Using Procmon, file system access is captured showing the traversal in action.

Example command to read Serv-U-StartupLog.txt:


Tactics, Techniques, and Procedures (TTPs)

  • Initial Access: Exploiting CVE-2024-28995 to gain unauthorized file access.

  • Execution: Sending crafted HTTP requests to the vulnerable endpoint.

  • Credential Access: Accessing files containing credentials or other sensitive information.

  • Discovery: Reading configuration and log files to understand system details.

  • Collection: Exfiltrating sensitive data from the compromised system.

YARA Rule for Detection

A YARA rule can help detect attempts to exploit this vulnerability by looking for common directory traversal patterns.


Apply the hotfix provided by SolarWinds immediately to mitigate the vulnerability. Additionally, monitor network traffic for unusual patterns, implement strict input validation, and use intrusion detection systems to detect and prevent exploitation attempts.

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