CVE-2018-1337 in LDAP API
Summary
by MITRE
In Apache LDAP API before 1.0.2, a bug in the way the SSL Filter was setup made it possible for another thread to use the connection before the TLS layer has been established, if the connection has already been used and put back in a pool of connections, leading to leaking any information contained in this request (including the credentials when sending a BIND request).
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Analysis
by VulDB Data Team • 03/01/2020
The vulnerability identified as CVE-2018-1337 represents a critical security flaw in Apache LDAP API versions prior to 1.0.2 that exposes sensitive data through improper SSL/TLS connection handling. This issue specifically affects the SSL filter implementation within the LDAP connection pooling mechanism, creating a race condition that can result in credential exposure and data leakage during authentication operations. The vulnerability arises from a fundamental flaw in how the LDAP API manages thread synchronization when reusing pooled connections with TLS encryption.
The technical root cause of this vulnerability lies in the improper initialization sequence of the SSL/TLS layer within the connection pooling framework. When a connection is returned to the pool after initial use, the SSL filter setup process does not adequately ensure that the TLS handshake has completed before the connection becomes available for reuse by another thread. This race condition allows a second thread to attempt to use the connection while the TLS layer is still being established, creating a window where sensitive information can be transmitted in plaintext or where authentication credentials may be exposed during BIND operations. The flaw is particularly dangerous because it operates at the protocol level where authentication credentials are typically transmitted.
The operational impact of this vulnerability extends beyond simple credential leakage to encompass broader security implications for LDAP-based authentication systems. Attackers can exploit this vulnerability to capture authentication tokens, user credentials, and potentially sensitive directory information during the brief period when the TLS layer is not fully established. This weakness directly violates the principle of secure communication and can enable unauthorized access to directory services, particularly in environments where LDAP is used for user authentication and authorization. The vulnerability is especially concerning in enterprise environments where LDAP is commonly used for single sign-on and directory services.
Mitigation strategies for CVE-2018-1337 require immediate patching of affected Apache LDAP API versions to 1.0.2 or later, which includes the corrected SSL filter implementation that properly synchronizes connection reuse with TLS establishment. Organizations should also implement connection pooling configurations that enforce strict TLS handshake completion before connection availability, and consider disabling connection pooling in high-security environments until proper TLS initialization is confirmed. Additionally, network monitoring should be enhanced to detect anomalous LDAP traffic patterns that may indicate exploitation attempts. This vulnerability aligns with CWE-362, which addresses race conditions in concurrent programming, and maps to ATT&CK technique T1078.002 for valid accounts and T1566.001 for spearphishing attachments, as it enables credential compromise through improper protocol handling.