In May 2022, Microsoft patched a serious security issue tracked as CVE-2022-29141—a Windows LDAP Remote Code Execution Vulnerability. This vulnerability gained attention as it had the potential for remote code execution (RCE) by simply sending specially-crafted requests to a vulnerable Windows LDAP server. Unlike related CVEs (such as CVE-2022-22012, CVE-2022-22013, CVE-2022-22014, CVE-2022-29128, CVE-2022-29129, CVE-2022-29130, CVE-2022-29131, CVE-2022-29137, and CVE-2022-29139), CVE-2022-29141 stands alone for its specific exploit path and impacts.

In this article, let’s break down what this vulnerability is, see how it could be exploited, and find out how to protect your environment.

What is CVE-2022-29141?

CVE-2022-29141 is a vulnerability in the Windows Lightweight Directory Access Protocol (LDAP) that can allow an attacker to execute arbitrary code within the context of the LDAP service. LDAP is widely used for directory services across enterprise networks, making this bug especially dangerous in Windows domains.

Impact: Remote Code Execution (RCE).

- CVSS Score: High (usually 8.1, but confirm from MSRC guidance).

Official Advisory

- Microsoft Security Response Center (MSRC) CVE-2022-29141 Advisory
- NVD listing for CVE-2022-29141

What Makes CVE-2022-29141 Unique?

This CVE specifically covers an input validation failure in how Windows LDAP Server handles specially-crafted application protocol data units (APDUs). Unlike its neighboring vulnerabilities (such as CVE-2022-22012 or CVE-2022-29128), which target related but different logic flaws, CVE-2022-29141 can be triggered by unauthenticated attackers.

The Vulnerability: Technical Details

The bug is triggered when the LDAP service parses APDUs from clients. In vulnerable versions, certain crafted requests can cause an out-of-bounds memory write or use-after-free scenario, resulting in possible code execution.

> Note: Full technical details and Proof-of-Concept (PoC) exploits were not public at release, but security researchers have since discussed possible exploit strategies.

Example Attack Path

An attacker could send a malformed LDAP search or bind request to the vulnerable server. This could be as simple as the following:

Pseudocode of Malicious Packet

import socket

ldap_server = "192.168.1.10"
port = 389 # LDAP
malicious_packet = b"\x30\x81\xA2..."  # ASN.1 BER-encoded payload with underflow/excessive lengths

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.connect((ldap_server, port))
    s.sendall(malicious_packet)

The malicious_packet would contain a specifically crafted ASN.1 structure that, when parsed, triggers the bug inside the Windows LDAP server.

Exploitation Details & Scenarios

Precondition: The LDAP server is reachable on the network and unpatched.

Attack Steps

1. Network Access: Attacker can reach TCP/389 (LDAP) or TCP/636 (LDAPS) on Windows Domain Controller or another LDAP server.

Send Malformed Requests: Attacker transmits a crafted APDU triggering the bug.

3. Trigger Code Execution: Server parses request, causing memory corruption and possible execution of attacker-controlled code.

Sample Exploit Skeleton

Exploit code for this vulnerability is not officially available, but here’s a basic structure that a typical RCE exploit might use:

import socket

def send_malicious_ldap_request(target_ip, port):
    # Your crafted payload goes here
    malicious_data = b'\x30\x82\x02\x01...'
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((target_ip, port))
    s.send(malicious_data)
    s.close()

if __name__ == "__main__":
    send_malicious_ldap_request("10...5", 389)

*Remember*: The above payload is illustrative. Actual exploitation would require reverse-engineering the ASN.1 request parser and developing precise memory corruption primitives.

Mitigation Strategies

1. Apply Patches: Microsoft has issued updates. Install the latest security update.
2. Limit Network Exposure: Block LDAP/LDAPS from untrusted networks.

Apply Registry Hardening: Microsoft suggests hardened registry settings for LDAP

- LDAP Channel Binding and LDAP Signing Requirements

References & Further Reading

- Microsoft: CVE-2022-29141
- Qualys Analysis: Patch Tuesday May 2022
- NVD Entry
- LDAP Security Guidance

Conclusion

CVE-2022-29141 is a prime example of why LDAP exposure is dangerous on untrusted networks. As a remote, unauthenticated code execution bug, it has all the properties attackers look for in a wormable vulnerability—especially in enterprise environments. While public exploits are rare, the simplicity of the attack path means organizations must prioritize patching and hardening right away.

Stay safe: Patch early, restrict LDAP access, and always monitor your network traffic.

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Timeline

Published on: 05/10/2022 21:15:00 UTC
Last modified on: 05/23/2022 17:29:00 UTC