CVE-2017-7488 in Authconfig
Summary
by MITRE
Authconfig version 6.2.8 is vulnerable to an Information exposure while using SSSD to authenticate against remote server resulting in the leak of information about existing usernames.
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Analysis
by VulDB Data Team • 12/24/2020
The vulnerability identified as CVE-2017-7488 affects authconfig version 628 which is part of the Red Hat Enterprise Linux authentication management framework. This issue specifically manifests when the system utilizes SSSD or System Security Services Daemon for authentication purposes against remote servers. The flaw represents a significant security weakness that allows attackers to gain unauthorized knowledge about valid usernames within the system. The vulnerability stems from improper handling of authentication responses during the SSSD authentication process, where sensitive information about user accounts becomes inadvertently exposed through error messages or response patterns.
The technical implementation of this vulnerability involves the interaction between authconfig and SSSD components during authentication workflows. When attempting to authenticate against remote servers, the system fails to properly sanitize or obscure authentication responses that contain information about account existence. This occurs because the authentication process does not adequately distinguish between different types of authentication failures, such as non-existent accounts versus network connectivity issues. The information exposure typically manifests in the form of subtle differences in response times, error messages, or connection handling that can be analyzed by attackers to determine which usernames are valid within the system. This type of vulnerability falls under the CWE-200 category of "Information Exposure" and represents a classic example of how authentication systems can leak information about their internal state.
The operational impact of CVE-2017-7488 is substantial as it provides attackers with a foothold for further exploitation attempts. By discovering valid usernames, threat actors can conduct targeted brute force attacks, credential stuffing campaigns, or social engineering operations with significantly higher success rates. The vulnerability essentially creates a reconnaissance tool in the hands of attackers, allowing them to map out user populations without requiring additional credentials or complex attack vectors. This information leakage can be particularly damaging in environments where user enumeration leads to privilege escalation opportunities or where the exposure of legitimate usernames enables more sophisticated attack patterns. The attack pattern aligns with ATT&CK technique T1078 which covers valid accounts and credential access, as this vulnerability provides attackers with legitimate account information that can be leveraged for unauthorized access.
Mitigation strategies for CVE-2017-7488 should focus on both immediate patching and configuration hardening measures. The primary solution involves updating authconfig to version 629 or later where the vulnerability has been addressed through proper response sanitization and authentication flow management. Organizations should also implement proper rate limiting and account lockout mechanisms to prevent abuse of the information exposure. Configuration changes can include disabling SSSD user enumeration features, implementing consistent error handling across authentication responses, and ensuring that all authentication systems return uniform responses regardless of whether the account exists. Network-level protections such as intrusion detection systems can help monitor for unusual authentication patterns that might indicate exploitation attempts. Additionally, implementing multi-factor authentication and regular security audits of authentication systems can provide defense-in-depth measures against exploitation of this vulnerability. The remediation process should also include comprehensive testing to ensure that no other authentication components within the system exhibit similar information leakage characteristics.