CVE-2016-5747 in eDirectory
Summary
by MITRE
A security vulnerability in cookie handling in the http stack implementation in NDSD in Novell eDirectory before 9.0.1 allows remote attackers to bypass intended access restrictions by leveraging predictable cookies.
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Analysis
by VulDB Data Team • 09/11/2020
The vulnerability identified as CVE-2016-5747 represents a critical weakness in the cookie management system of Novell eDirectory's NDSD component, specifically within its HTTP stack implementation. This flaw resides in the way the system generates and validates session cookies, creating a pathway for malicious actors to circumvent access controls that are meant to protect sensitive network resources. The vulnerability affects all versions of Novell eDirectory prior to 9.0.1, making it a significant concern for organizations that have not yet upgraded their directory services infrastructure. The issue is particularly dangerous because it operates at the network protocol level, affecting the fundamental security mechanisms that govern user authentication and authorization within the directory service environment.
The technical root cause of this vulnerability stems from predictable cookie generation algorithms that do not adequately randomize session identifiers. When NDSD generates cookies for HTTP sessions, it employs a methodology that produces cookies with insufficient entropy or cryptographic strength, allowing attackers to predict future cookie values based on observed patterns. This predictability enables attackers to craft valid session tokens that can be used to impersonate legitimate users and gain unauthorized access to directory services. The vulnerability operates under CWE-330, which specifically addresses the use of weak entropy sources in cryptographic operations, and aligns with ATT&CK technique T1566 for credential harvesting through social engineering and session hijacking. The flaw essentially undermines the session management security model by providing attackers with a method to bypass authentication mechanisms through cookie manipulation.
The operational impact of CVE-2016-5747 extends beyond simple unauthorized access to encompass potential data breaches, privilege escalation, and complete compromise of directory service integrity. Attackers leveraging this vulnerability can access sensitive user information, modify directory entries, and potentially establish persistent access points within the network infrastructure. Given that eDirectory serves as a foundational component for many enterprise directory services, the compromise of a single instance can cascade into broader network security failures. The vulnerability is particularly concerning in environments where eDirectory is used for authentication services, as it could enable attackers to move laterally across the network using stolen session tokens. Organizations may experience unauthorized modifications to user accounts, group memberships, and access control lists, all while maintaining the appearance of legitimate system behavior.
Mitigation strategies for CVE-2016-5747 must prioritize immediate remediation through the installation of the official Novell eDirectory 9.0.1 patch or later versions that address the predictable cookie generation issue. System administrators should also implement additional monitoring measures to detect anomalous cookie usage patterns and potential exploitation attempts. Network segmentation and access control measures can provide additional defense layers, while regular security audits should verify that cookie generation mechanisms meet current cryptographic standards. Organizations should also consider implementing session management policies that enforce shorter session timeouts and require re-authentication for sensitive operations. The vulnerability serves as a reminder of the critical importance of proper entropy in session management and highlights the necessity of following established security frameworks such as NIST SP 800-63 for authentication and session management best practices. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other components of the directory service infrastructure.