CVE-2011-3372 in IMAPd
Summary
by MITRE
imap/nntpd.c in the NNTP server (nntpd) for Cyrus IMAPd 2.4.x before 2.4.12 allows remote attackers to bypass authentication by sending an AUTHINFO USER command without sending an additional AUTHINFO PASS command.
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Analysis
by VulDB Data Team • 08/06/2024
The vulnerability identified as CVE-2011-3372 resides within the NNTP server component of Cyrus IMAPd version 2.4.x prior to 2.4.12. This flaw represents a critical authentication bypass issue that fundamentally undermines the security model of the NNTP service. The vulnerability specifically affects the authentication handling mechanism where the system fails to properly validate the completeness of authentication sequences. When an attacker sends an AUTHINFO USER command without subsequently providing the required AUTHINFO PASS command, the system erroneously grants access to the user account, effectively allowing unauthorized access to the NNTP service. This represents a classic example of improper input validation and authentication flow control.
The technical implementation of this vulnerability stems from a design flaw in the nntpd.c file where the authentication state machine does not properly enforce the sequential nature of authentication commands. According to CWE-287, this vulnerability falls under improper authentication, specifically the category of authentication bypass through incomplete authentication sequences. The flaw allows attackers to establish a session with a valid username without providing the corresponding password, creating a window of opportunity for unauthorized access. This type of vulnerability is particularly dangerous in network services where authentication is critical for access control and data protection.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential data compromise and service disruption. An attacker could leverage this weakness to gain access to NNTP server resources, potentially including email messages, newsgroup postings, and other sensitive data stored within the Cyrus IMAPd system. The vulnerability aligns with ATT&CK technique T1078.002, which covers legitimate credentials, as attackers can use the authenticated session to perform further malicious activities. The impact is particularly severe because the NNTP service often provides access to email and newsgroup content that may contain sensitive business information, personal communications, or confidential data. Additionally, this vulnerability could serve as a stepping stone for more sophisticated attacks within a network infrastructure.
Mitigation strategies for CVE-2011-3372 should focus on immediate patching of the affected Cyrus IMAPd versions to 2.4.12 or later, which contains the necessary fixes for proper authentication sequence validation. Organizations should also implement network segmentation to limit access to NNTP services, employ robust monitoring of authentication attempts, and consider disabling NNTP services if they are not essential to operations. Security teams should review and test their authentication policies to ensure that incomplete authentication sequences are properly rejected by the system. The vulnerability demonstrates the importance of proper state management in authentication protocols and serves as a reminder of the critical need for thorough input validation and sequence verification in security-sensitive applications. Organizations should also consider implementing additional layers of security such as firewall rules, intrusion detection systems, and regular security audits to prevent exploitation of similar authentication bypass vulnerabilities.