CVE-2000-1000 in Instant Messenger
Summary
by MITRE
Format string vulnerability in AOL Instant Messenger (AIM) 4.1.2010 allows remote attackers to cause a denial of service and possibly execute arbitrary commands by transferring a file whose name includes format characters.
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Analysis
by VulDB Data Team • 04/06/2019
The vulnerability identified as CVE-2000-1000 represents a critical format string flaw in AOL Instant Messenger version 4.1.2010 that exposes users to significant security risks. This vulnerability specifically affects the client-side application during file transfer operations, where the software fails to properly sanitize user-provided filenames before processing them through format string functions. The flaw stems from improper input validation mechanisms that allow malicious actors to inject format specifiers such as %s, %d, or %x into filenames, which are then interpreted by the application's string formatting routines without adequate protection against malicious input.
The technical exploitation of this vulnerability occurs when an attacker sends a file to a victim user through AIM's file transfer mechanism, where the filename contains specially crafted format string sequences. When the vulnerable client attempts to display or process the filename, the format string functions execute these sequences, potentially leading to stack corruption, memory access violations, or arbitrary code execution. This type of vulnerability is classified under CWE-134, which specifically addresses the use of format strings without proper validation, making it susceptible to both denial of service attacks and remote code execution scenarios. The vulnerability operates at the application layer and can be exploited without requiring authentication, making it particularly dangerous in networked environments where users frequently exchange files through instant messaging platforms.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable complete system compromise. When exploited successfully, attackers can manipulate the application's memory layout, cause crashes, or even execute arbitrary code with the privileges of the affected user. The vulnerability affects the core functionality of AIM's file transfer system, disrupting normal communication patterns and potentially allowing unauthorized access to sensitive information. The attack vector is particularly concerning as it requires minimal user interaction beyond accepting a file transfer, making it an attractive target for social engineering attacks where users might unknowingly accept malicious files from untrusted sources. The vulnerability also demonstrates a fundamental flaw in input sanitization practices that were common in legacy software applications of that era.
Mitigation strategies for CVE-2000-1000 should prioritize immediate software updates and patches from AOL, as the vulnerability affects a specific version of the client software. System administrators should implement network-level controls to monitor and restrict file transfer protocols within their environments, particularly when dealing with instant messaging applications. The implementation of proper input validation and sanitization mechanisms should be enforced across all applications handling user-provided data, following established security best practices and principles outlined in the ATT&CK framework under the technique of T1059 for command and scripting interpreter. Organizations should also consider deploying network monitoring tools to detect anomalous file transfer activities and implement user education programs to raise awareness about the risks of accepting files from untrusted sources. Additionally, the vulnerability highlights the importance of secure coding practices, specifically avoiding direct use of user input in format string functions and implementing proper parameter validation before any string processing occurs.