CVE-2011-3208 in Cyrus IMAP Server
Summary
by MITRE
Stack-based buffer overflow in the split_wildmats function in nntpd.c in nntpd in Cyrus IMAP Server before 2.3.17 and 2.4.x before 2.4.11 allows remote attackers to execute arbitrary code via a crafted NNTP command.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability CVE-2011-3208 represents a critical stack-based buffer overflow affecting the Cyrus IMAP server's NNTP implementation. This flaw exists within the split_wildmats function in the nntpd.c file, which processes wildcard patterns in NNTP commands. The vulnerability affects versions prior to 2.3.17 and 2.4.11, making it a significant concern for organizations running older installations of the Cyrus IMAP server. The buffer overflow occurs when processing specially crafted NNTP commands that contain excessive wildcard pattern data, allowing remote attackers to overwrite adjacent memory on the stack.
The technical exploitation of this vulnerability follows a classic stack-based buffer overflow pattern where insufficient input validation leads to memory corruption. When the split_wildmats function processes NNTP commands containing malformed wildcard patterns, it fails to properly bounds-check the input data before copying it into a fixed-size stack buffer. This allows an attacker to overflow the buffer and overwrite return addresses, saved registers, and other critical stack data. The vulnerability is classified as CWE-121 Stack-based Buffer Overflow, which is a well-documented and frequently exploited weakness in network services. The ATT&CK framework categorizes this as a code injection technique under the T1059.007 sub-technique, specifically targeting remote code execution through protocol parsing flaws.
The operational impact of this vulnerability is severe as it enables remote code execution without authentication, potentially allowing attackers to gain complete control over affected systems. Since NNTP services are often exposed to the internet and may be used for legitimate mail relay operations, this vulnerability presents a significant risk to email infrastructure. An attacker could leverage this flaw to execute arbitrary code with the privileges of the nntpd process, typically running as a system user or daemon account. The vulnerability could be exploited to establish persistent backdoors, exfiltrate sensitive data, or use the compromised server as a launch point for further attacks within the network. Organizations running vulnerable versions of Cyrus IMAP server face potential data breaches, service disruption, and compromise of their entire email infrastructure.
Mitigation strategies for this vulnerability involve immediate patching of affected systems to versions 2.3.17 or 2.4.11 and later. System administrators should also implement network segmentation to limit exposure of NNTP services to trusted networks only, and consider disabling NNTP services if they are not required for operations. Additional defensive measures include implementing intrusion detection systems to monitor for suspicious NNTP command patterns and conducting regular security assessments of email infrastructure. The vulnerability demonstrates the importance of proper input validation and bounds checking in network services, reinforcing the principle of defense in depth. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and maintain comprehensive inventory of all running services and their versions to quickly identify vulnerable components.