CVE-2005-1522 in Mailutils
Summary
by MITRE
The imap4d server for GNU Mailutils 0.5 and 0.6, and other versions before 0.6.90, allows authenticated remote users to cause a denial of service (CPU consumption) via a large range value in the FETCH command.
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Analysis
by VulDB Data Team • 06/02/2019
The vulnerability identified as CVE-2005-1522 affects the imap4d server component within GNU Mailutils versions 0.5 through 0.6.89, representing a significant security flaw that enables authenticated remote attackers to induce denial of service conditions through strategic manipulation of the FETCH command. This issue stems from inadequate input validation mechanisms within the server's processing of range parameters, creating a scenario where maliciously crafted requests can consume excessive computational resources. The vulnerability operates at the application layer within the Internet Message Access Protocol (IMAP) implementation, specifically targeting the server's handling of message retrieval operations that involve range specifications. The flaw represents a classic resource exhaustion attack vector that can severely impact system availability and performance.
The technical implementation of this vulnerability exploits the server's failure to properly validate or limit the range values submitted during FETCH operations, allowing attackers to specify extremely large numerical values that cause the server to perform excessive CPU processing. When the imap4d server receives a FETCH command with an oversized range parameter, it attempts to process the request through inefficient algorithms that iterate through potentially enormous ranges, leading to substantial CPU utilization and system responsiveness degradation. This behavior aligns with CWE-770, which describes allocation of resources without proper limits or controls, and manifests as a form of computational resource exhaustion that can be exploited to overwhelm system capabilities.
The operational impact of CVE-2005-1522 extends beyond simple service disruption to encompass broader system stability concerns, particularly in environments where email services are critical for business operations. An authenticated attacker with legitimate credentials can leverage this vulnerability to consume system resources, potentially leading to complete service unavailability for other legitimate users. The vulnerability's exploitation requires only authentication credentials, making it particularly dangerous as it can be triggered by insiders or compromised accounts. The server's response time degrades significantly during exploitation, with CPU usage potentially reaching 100% utilization, effectively preventing legitimate users from accessing their email services. This type of attack aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion.
Mitigation strategies for this vulnerability involve immediate patching to GNU Mailutils versions 0.6.90 and later, which contain proper input validation and range limiting mechanisms. System administrators should implement rate limiting controls on IMAP operations to prevent excessive processing of individual requests, and establish monitoring protocols to detect unusual CPU consumption patterns. Network-level firewalls can be configured to limit the frequency of FETCH operations from individual clients, while server configuration should enforce reasonable limits on range parameter values. The fix implemented in version 0.6.90 incorporates proper bounds checking and input sanitization that prevents the processing of excessively large range values, effectively neutralizing the resource exhaustion potential. Additionally, organizations should consider implementing intrusion detection systems to monitor for patterns consistent with this specific attack vector, and maintain regular security updates to address similar vulnerabilities in email infrastructure components.