CVE-2016-7142 in InspIRCd
Summary
by MITRE
The m_sasl module in InspIRCd before 2.0.23, when used with a service that supports SASL_EXTERNAL authentication, allows remote attackers to spoof certificate fingerprints and consequently log in as another user via a crafted SASL message.
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Analysis
by VulDB Data Team • 09/23/2024
The vulnerability identified as CVE-2016-7142 affects the m_sasl module within InspIRCd versions prior to 2.0.23, representing a critical authentication bypass flaw that undermines the security of SASL_EXTERNAL authentication mechanisms. This vulnerability specifically targets services that implement certificate-based authentication, where the module fails to properly validate certificate fingerprints presented by clients during the authentication process. The flaw exists in the module's handling of SASL messages, allowing malicious actors to manipulate authentication exchanges by crafting specially crafted messages that appear to contain legitimate certificate fingerprints. The vulnerability stems from insufficient input validation and authentication verification within the m_sasl module, creating a pathway for unauthorized access that directly compromises the integrity of the authentication system.
The technical implementation of this vulnerability exploits the trust model inherent in certificate-based authentication systems where the server relies on certificate fingerprints to verify client identity. When a client attempts to authenticate using SASL_EXTERNAL, the module should validate that the presented certificate matches the expected fingerprint for the target user account. However, due to flawed validation logic in the m_sasl module, attackers can construct malicious SASL messages containing forged certificate fingerprints that the server accepts as legitimate. This allows an attacker to impersonate any user whose certificate fingerprint they can guess or obtain, effectively bypassing the authentication mechanism entirely. The vulnerability specifically impacts the authentication flow where certificate fingerprints are used as the primary means of user identification, making it particularly dangerous in environments where certificate-based authentication is the primary security control.
The operational impact of CVE-2016-7142 extends beyond simple unauthorized access, as it enables attackers to assume the identity of legitimate users within the IRC network, potentially gaining access to sensitive channels, private messages, and privileged commands. This authentication bypass can lead to complete compromise of user accounts, enabling attackers to perform actions such as channel manipulation, message spoofing, and privilege escalation within the network. The vulnerability affects the fundamental security guarantees of certificate-based authentication, undermining the trust relationship between the server and authenticated clients. Organizations relying on InspIRCd for secure communications may experience unauthorized access to confidential data, disruption of services, and potential data breaches. The impact is particularly severe in environments where IRC networks serve as communication channels for sensitive operations or where users maintain elevated privileges within the network infrastructure.
Mitigation strategies for CVE-2016-7142 primarily focus on upgrading to InspIRCd version 2.0.23 or later, which contains the necessary patches to address the flawed certificate validation logic in the m_sasl module. Administrators should also implement additional security controls such as monitoring authentication logs for suspicious activity patterns and implementing stricter certificate management policies. The vulnerability aligns with CWE-287, which addresses improper authentication issues, and maps to ATT&CK technique T1078.004 for valid accounts, as attackers can leverage this flaw to obtain and use valid user credentials through certificate impersonation. Network administrators should also consider implementing additional authentication layers, such as multi-factor authentication, and regularly audit their authentication mechanisms to prevent similar vulnerabilities from being exploited in other modules or components of their IRC infrastructure.