CVE-2019-11187 in GOsa
Summary
by MITRE
Incorrect Access Control in the LDAP class of GONICUS GOsa through 2019-04-11 allows an attacker to log into any account with a username containing the case-insensitive substring "success" when an arbitrary password is provided.
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Analysis
by VulDB Data Team • 07/29/2020
The vulnerability CVE-2019-11187 represents a critical access control flaw within the Lightweight Directory Access Protocol implementation of the GONICUS GOsa web application. This issue affects versions through 2019-04-11 and demonstrates a fundamental failure in authentication logic that could enable unauthorized access to user accounts. The vulnerability stems from improper validation of username inputs during the LDAP authentication process, creating a dangerous condition where attackers can exploit specific username patterns to bypass normal authentication mechanisms.
The technical exploitation of this vulnerability relies on the application's case-insensitive substring matching logic within the LDAP class implementation. When an attacker provides an arbitrary password, the system incorrectly processes usernames containing the substring "success" in any case combination, effectively granting access to any account that meets this criteria. This flaw operates at the authentication layer and represents a classic example of insecure input validation where the application fails to properly sanitize or validate user-provided identifiers before processing them through the LDAP authentication pipeline. The vulnerability is classified under CWE-287 which addresses improper authentication issues, specifically focusing on authentication bypass through flawed credential validation mechanisms.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it could enable attackers to escalate privileges and gain administrative control over user accounts within the GOsa environment. Since the vulnerability operates at the core authentication layer, successful exploitation could result in complete compromise of the directory services, potentially allowing attackers to access sensitive organizational data, modify user permissions, or establish persistent access points within the network infrastructure. The case-insensitive nature of the vulnerability means that attackers could use variations such as "SUCCESS", "Success", or "succeSS" to exploit the flaw, making detection and prevention more challenging. This vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation through legitimate credentials.
Mitigation strategies for CVE-2019-11187 require immediate patching of the affected GOsa versions to address the flawed LDAP authentication logic and implement proper input validation. Organizations should also consider implementing additional authentication controls such as multi-factor authentication to reduce the impact of credential-based attacks. Network segmentation and monitoring of authentication attempts can help detect exploitation attempts, while regular security audits of authentication mechanisms should be conducted to identify similar vulnerabilities. The fix should ensure that username validation occurs before LDAP authentication processing and that substring matching operations are properly constrained to prevent unintended access patterns. Security teams should also review and test all authentication-related code changes to prevent regression issues that could introduce similar vulnerabilities in the future.