CVE-2005-1655 in Instant Messenger
Summary
by MITRE
AOL Instant Messenger 5.5.x and earlier allows remote attackers to cause a denial of service (client crash) via an invalid smiley icon location in the sml parameter of a font tag.
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Analysis
by VulDB Data Team • 06/01/2019
The vulnerability identified as CVE-2005-1655 represents a classic buffer overflow condition within AOL Instant Messenger version 5.5.x and earlier systems. This flaw manifests when the client application processes malformed HTML content containing a font tag with an invalid smiley icon location specified in the sml parameter. The issue stems from inadequate input validation and boundary checking mechanisms within the IM client's HTML parser, which fails to properly sanitize user-supplied data before processing. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, where the application writes beyond the allocated memory boundaries when handling the malformed smiley icon path. This type of vulnerability falls within the ATT&CK framework under T1499.004 for Network Denial of Service, specifically targeting client-side applications through malformed content delivery.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a specially formatted message containing a font tag with an invalid sml parameter value that exceeds the buffer capacity allocated for smiley icon paths. When the AOL IM client processes this malformed content, it attempts to parse and display the smiley icon while the buffer overflow occurs during the string handling operations. The client application crashes immediately upon encountering the malformed data, resulting in a complete denial of service for the targeted user. This vulnerability affects all versions of AOL Instant Messenger up to and including version 5.5.x, making it a widespread issue across numerous client installations during that period.
The operational impact of CVE-2005-1655 extends beyond simple client crashes, as it provides attackers with a reliable method to disrupt communication services for targeted users or entire networks. The vulnerability can be exploited through various attack vectors including instant messaging conversations, chat room messages, or even through malicious web content that gets automatically processed by the IM client. The ease of exploitation makes this a particularly dangerous vulnerability since attackers need only send a single malformed message to cause service disruption. This type of denial of service attack can be amplified through automated tools that generate multiple malicious messages simultaneously, potentially affecting multiple users within a network or organization. The vulnerability demonstrates poor secure coding practices and highlights the importance of proper input validation in client-side applications.
Mitigation strategies for CVE-2005-1655 require immediate implementation of software updates and patches provided by AOL to address the buffer overflow condition in the HTML parsing component. System administrators should ensure all AOL Instant Messenger clients are upgraded to version 5.6 or later, which includes proper input validation for font tag parameters and sml attribute handling. Network-level defenses should include filtering of instant messaging traffic to prevent the delivery of malformed HTML content, particularly focusing on font tag processing within IM protocols. Organizations should implement application whitelisting policies that restrict the execution of untrusted IM content and consider deploying network-based intrusion prevention systems that can detect and block malformed HTML sequences. The vulnerability serves as a prime example of why proper secure coding practices including bounds checking, input sanitization, and proper error handling are essential in client applications to prevent remote code execution and denial of service conditions.