Vulnerabilities of Lightweight Directory Access Protocol (LDAP): An Analysis with CVE References

Abstract

The Lightweight Directory Access Protocol (LDAP) is a widely adopted protocol for accessing and managing directory services, such as Microsoft’s Active Directory, in enterprise networks. While LDAP provides efficient user authentication and directory management, its implementation and configuration can expose significant security vulnerabilities. This paper explores the vulnerabilities associated with LDAP, focusing on specific CVE-identified flaws, their exploitation mechanisms, and their impact on network security. Recent examples, such as CVE-2024-49112 and CVE-2024-49113, are analyzed to highlight the severity of LDAP-related risks. Mitigation strategies and best practices are proposed to secure LDAP deployments effectively.

Introduction

LDAP, developed as a lightweight alternative to the Directory Access Protocol (DAP), is a vendor-neutral protocol used to query and manage directory information over TCP/IP networks. It is integral to identity and access management (IAM) systems, particularly in Windows environments via Active Directory. However, its widespread use and powerful querying capabilities make it a prime target for attackers. Vulnerabilities in LDAP implementations can lead to unauthorized access, remote code execution (RCE), denial-of-service (DoS) attacks, and data leaks. This paper examines these vulnerabilities, leveraging CVE data to provide concrete examples, and discusses how organizations can mitigate these risks.

LDAP Vulnerabilities: An Overview

LDAP vulnerabilities typically arise from misconfigurations, insufficient input validation, or flaws in the underlying protocol or its implementations. These issues can be exploited to bypass authentication, escalate privileges, or disrupt services. The following sections detail notable categories of LDAP vulnerabilities, supported by recent CVE examples.

1. Remote Code Execution (RCE) Vulnerabilities

RCE vulnerabilities allow attackers to execute arbitrary code on a target system, often with elevated privileges. In LDAP, such flaws typically stem from improper handling of LDAP queries or responses.

  • CVE-2024-49112: Disclosed by Microsoft on December 10, 2024, this critical vulnerability in Windows LDAP carries a CVSS score of 9.8. It arises from an integer overflow in LDAP-related code, enabling an unauthenticated attacker to execute arbitrary code by sending specially crafted RPC calls to a vulnerable Domain Controller (DC). Exploitation could compromise entire domains, making it a high-priority patching target. Researchers at SafeBreach developed a proof-of-concept (PoC) exploit, “LDAPNightmare,” demonstrating its zero-click potential to crash unpatched servers or execute code within the LDAP service context.
  • CVE-2022-29128: Another Windows LDAP RCE vulnerability, this flaw allows a remote attacker to execute code by tricking a victim into connecting to a malicious LDAP server. It highlights the risks of insufficient input validation, a recurring issue in LDAP implementations.

These RCE vulnerabilities underscore the critical role of Domain Controllers in enterprise networks and the catastrophic impact of their compromise.

2. Denial-of-Service (DoS) Vulnerabilities

DoS vulnerabilities disrupt service availability, often by crashing servers or overwhelming resources. LDAP’s reliance on TCP handshakes and query processing makes it susceptible to such attacks.

  • CVE-2024-49113: Patched alongside CVE-2024-49112 in December 2024, this DoS vulnerability in Windows LDAP (CVSS score: 7.5) results from an integer overflow in wldap32.dll, the LDAP client library. SafeBreach’s “LDAPNightmare” PoC exploit crashes unpatched Windows servers by triggering a malicious CLDAP referral response, causing the Local Security Authority Subsystem Service (LSASS) to fail and reboot the server. This flaw affects not only Domain Controllers but any unpatched Windows Server with internet-connected DNS, amplifying its reach.
  • Historical Context: Research from 2010 demonstrated DoS attacks exploiting LDAP’s TCP three-way handshake, indicating that such vulnerabilities have persisted over time due to protocol design and implementation weaknesses.
3. Information Disclosure and Injection Attacks

LDAP’s role in storing sensitive data, such as user credentials, makes it vulnerable to information disclosure and injection attacks.

  • CVE-2025-1075: Identified in Checkmk versions prior to 2.3.0p27, this flaw causes LDAP credentials to be logged in plain text, exposing them to unauthorized access. While not a direct LDAP protocol issue, it reflects the risks of integrating LDAP with poorly secured applications.
  • LDAP Injection: Similar to SQL injection, LDAP injection exploits unsanitized user input to manipulate queries. For example, attackers can use metacharacters (e.g., *, &) to bypass authentication or extract directory data. Though not tied to a specific CVE, this technique remains a prevalent threat due to inadequate input validation in LDAP-reliant applications.
4. Misconfiguration and Exposure Risks

Misconfigured LDAP deployments, such as those exposing ports (e.g., 389 for LDAP, 636 for LDAPS) to the public internet, amplify vulnerability risks. Tools like BloodHound exploit LDAP enumeration to map network assets, aiding lateral movement. While not CVE-specific, this category underscores the importance of configuration in LDAP security.

Case Studies: Recent LDAP Exploits

  • CVE-2024-49112 and CVE-2024-49113: These twin vulnerabilities, discovered by Yuki Chen and patched in December 2024, exemplify LDAP’s dual RCE and DoS risks. The SafeBreach PoC demonstrated a sophisticated attack chain: an attacker sends a DCE/RPC request, manipulates DNS and NBNS responses, and delivers a malicious CLDAP referral to crash or control the target. The public release of exploit code heightened urgency for patching.
  • CVE-2024-12510: Affecting Xerox printers, this LDAP pass-back vulnerability allows attackers to capture authentication data, illustrating how LDAP integration in peripheral devices can introduce network-wide risks.

Impact on Enterprise Security

LDAP vulnerabilities threaten enterprise security by targeting critical infrastructure like Domain Controllers. Successful exploitation can lead to domain compromise, data breaches, or service outages. The high CVSS scores of recent CVEs (e.g., 9.8 for CVE-2024-49112) reflect their severity, while the availability of PoC exploits increases the likelihood of real-world attacks.

Mitigation Strategies

To secure LDAP deployments, organizations should adopt the following best practices:

  1. Patch Management: Apply security updates promptly, as demonstrated by Microsoft’s December 2024 patches for CVE-2024-49112 and CVE-2024-49113, which effectively mitigate these flaws.
  2. Network Segmentation: Isolate Domain Controllers from untrusted networks and restrict internet-facing LDAP ports (389, 636).
  3. Encryption: Use LDAPS (LDAP over SSL/TLS) to encrypt traffic, preventing interception and downgrade attacks.
  4. Input Validation: Ensure applications sanitize LDAP queries to thwart injection attacks.
  5. Monitoring and Detection: Implement monitoring for suspicious CLDAP responses, RPC calls, and DNS SRV queries, as recommended by SafeBreach for CVE-2024-49113.
  6. Access Control: Limit LDAP access to authenticated users and enforce strong authentication mechanisms, such as SASL or Kerberos.

Conclusion

LDAP’s critical role in directory services makes its vulnerabilities a significant concern for enterprise security. CVE-documented flaws like CVE-2024-49112 and CVE-2024-49113 highlight the protocol’s susceptibility to RCE and DoS attacks, while misconfigurations and injection risks further compound the threat landscape. By understanding these vulnerabilities and implementing robust mitigation strategies, organizations can safeguard their LDAP deployments against evolving cyber threats. Ongoing research and timely patching remain essential to maintaining the integrity of directory services.

References

  1. Microsoft Security Response Center. (2024). “CVE-2024-49112: Windows Lightweight Directory Access Protocol (LDAP) Remote Code Execution Vulnerability.”
  2. SafeBreach Labs. (2025). “LDAPNightmare: SafeBreach Publishes First PoC Exploit (CVE-2024-49113).”
  3. CVE Details. (2025). “CVE-2025-1075: Checkmk LDAP Credential Disclosure.”
  4. Rapid7 VulnDB. (2022). “CVE-2022-29128: Windows LDAP Remote Code Execution Vulnerability.”
  5. Unit 42, Palo Alto Networks. (2024). “LDAP Enumeration: Unveiling the Double-Edged Sword of Active Directory.”
  6. UpGuard. (n.d.). “LDAP Cybersecurity Risks and Prevention Techniques.”

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