This video is a detailed tutorial on the Log4J vulnerability (CVE-2021-44228), explaining its critical impact, how it works, and how to exploit and detect the vulnerability. Below is a breakdown of the key points covered:
1. Introduction to Log4J Vulnerability:
- The Log4J vulnerability, also known as Log4Shell, has been rated 10/10 in criticality due to its wide attack surface and the availability of exploits in the wild.
- This vulnerability is found in the Log4J Java logging library and affects many major companies and products, such as Apple, Twitter, Steam, Amazon, Minecraft, and more.
- Attackers are actively exploiting this vulnerability, which is why it is causing significant concern across the internet.
2. Affected Products and Resources:
- Many major companies use Log4J for logging purposes, and the video provides a reference to repositories listing affected products, such as Apache Struts, Minecraft, Cloudflare, WebEx, etc.
- A repository with URLs and discussions about mitigation steps for each affected product is mentioned, helping viewers understand where to look for patches and updates.
3. How Log4J Works:
- Log4J is a Java-based logging library used to log messages.
- The vulnerability allows attackers to execute code remotely by exploiting a JNDI (Java Naming and Directory Interface) lookup, particularly through the LDAP protocol.
4. Detection and Exploitation:
- Vulnerable Versions: Any Log4J version lower than 2.15.0 is vulnerable.
- Detection: The video demonstrates how to use a Python script to test if a web server is vulnerable to this exploit. The script opens an LDAP server on the attacker’s machine and waits for a connection back from the target server.
- If the target server connects back to the attacker’s LDAP server, it indicates that the target is vulnerable.
5. Running the Detection Script:
- A Python script is used to create a listening server on port 1389 (LDAP), and the target server is tested using this script.
- If the server is vulnerable, the connection would be established between the target server and the attacker’s machine, indicating a successful exploitation.
- The video shows how to test the vulnerability on a TryHackMe room using Apache Solr as the target product.
6. Exploit Example:
- The video shows how to manually test for the vulnerability using curl to send an HTTP request containing the exploit payload.
- The payload uses JNDI and LDAP to force the target server to connect back to the attacker’s server, indicating a successful exploitation attempt.
- The payload structure and path vary depending on the product being tested (e.g., Apache Solr or other Apache products).
7. Compiling the Exploit:
- The video demonstrates how to compile a Java class to exploit the vulnerability.
- Once the exploit is compiled and executed, the Netcat listener is used to detect whether the target server connects back to the attacker’s machine, confirming that it is vulnerable.
8. Conclusion:
- The tutorial emphasizes that this is just one method of testing for the vulnerability, and different products may require specific payloads and methods.
- It encourages users to look for patches and mitigation strategies provided by vendors and to stay vigilant in updating their systems to prevent exploitation.
In summary, this video provides a comprehensive overview of the Log4J vulnerability, explaining how it works, how to test for it, and how to exploit it, using both manual and automated methods. The video also includes hands-on examples of testing and detecting the vulnerability in real-time.
For more details on the above, watch the below walk-through videos
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