CVE-2004-2460 in gnubiff
Summary
by MITRE
Unknown vulnerability in POP3 in gnubiff before 2.0.0 allows remote attackers to cause a denial of service (application crash) via an "infinite" Unique IDentification Listing (UIDL) list.
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Analysis
by VulDB Data Team • 03/09/2015
The vulnerability identified as CVE-2004-2460 represents a significant denial of service weakness within the gnubiff email client's POP3 implementation. This issue affects versions prior to 2.0.0 and stems from the application's inability to properly handle malformed or excessively large UIDL responses from POP3 servers. The flaw manifests when a remote attacker manipulates the POP3 server to return an infinite or extremely large UIDL list, causing gnubiff to crash during processing. This type of vulnerability falls under the category of resource exhaustion attacks and specifically aligns with CWE-400, which addresses unspecified resource exhaustion conditions in software applications. The impact extends beyond simple application instability as it can be leveraged to disrupt email services for users relying on gnubiff for their communication needs.
The technical mechanism behind this vulnerability involves the POP3 protocol's UIDL command which is used to retrieve unique identifiers for messages on the server. When gnubiff processes the UIDL response, it fails to implement proper bounds checking or resource limiting mechanisms. This allows an attacker to craft a malicious POP3 server response that contains an excessive number of unique identifiers, potentially causing memory allocation issues or stack overflow conditions. The vulnerability is particularly concerning because it operates at the protocol level where the application processes network data without adequate validation of response sizes. The flaw demonstrates poor input validation practices and lacks proper defensive programming techniques that would prevent the application from being overwhelmed by unexpected data structures. This aligns with ATT&CK technique T1499.004 which covers network denial of service attacks and represents a classic example of how malformed network responses can be exploited to crash client applications.
The operational impact of this vulnerability extends beyond individual user disruption to potentially affect larger email infrastructure operations. When gnubiff crashes due to this issue, users lose access to their email notifications and may experience complete service interruption until the application is restarted. This vulnerability is particularly dangerous in environments where gnubiff is used as a background email monitoring service, as it could lead to missed critical communications and system reliability issues. The attack vector requires minimal sophistication from an attacker perspective since it only requires manipulation of the POP3 server response rather than complex exploitation techniques. Organizations using gnubiff for email monitoring should be particularly concerned as this vulnerability could be exploited to create persistent service disruptions. The vulnerability also highlights the importance of proper error handling in networked applications and demonstrates how simple protocol implementation flaws can lead to significant availability issues. This weakness represents a critical gap in the application's defensive programming practices and underscores the need for comprehensive input validation and resource management mechanisms in client applications that process external network data.
Mitigation strategies for this vulnerability should focus on implementing proper bounds checking and resource limiting within the UIDL processing code. Users should immediately upgrade to gnubiff version 2.0.0 or later where this issue has been resolved through proper input validation and memory management improvements. System administrators should also consider implementing network-level protections such as rate limiting and connection monitoring to detect and prevent malformed UIDL responses from reaching vulnerable applications. Additionally, organizations should conduct regular vulnerability assessments of their email client configurations and ensure that all applications processing network data implement proper defensive programming practices. The fix implemented in version 2.0.0 likely included enhanced input validation for UIDL responses and memory allocation limits to prevent the application from crashing when encountering unexpectedly large response sets. This vulnerability serves as a reminder of the importance of maintaining up-to-date security patches and implementing proper application hardening measures to protect against resource exhaustion attacks.