CVE-2000-1094 in Instant Messenger
Summary
by MITRE
Buffer overflow in AOL Instant Messenger (AIM) before 4.3.2229 allows remote attackers to execute arbitrary commands via a "buddyicon" command with a long "src" argument.
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Analysis
by VulDB Data Team • 04/18/2025
The vulnerability described in CVE-2000-1094 represents a critical buffer overflow flaw in AOL Instant Messenger version 4.3.2229 and earlier, which was widely deployed in the late 1990s and early 2000s. This vulnerability specifically affects the handling of the "buddyicon" command within the AIM client, where the application fails to properly validate the length of the "src" argument, creating an exploitable condition that allows remote attackers to execute arbitrary code on affected systems. The issue stems from improper bounds checking in the client-side implementation, where user-supplied data is directly copied into a fixed-size buffer without adequate length validation. This particular flaw aligns with CWE-121, which describes heap-based buffer overflow conditions, and also relates to CWE-787, concerning out-of-bounds write operations that can occur when input data exceeds the allocated buffer space. The vulnerability operates within the context of instant messaging protocols where clients receive and process data from remote peers, making it particularly dangerous in networked environments where malicious actors can craft specially crafted messages to exploit this weakness.
The technical exploitation of this vulnerability occurs when a remote attacker sends a specially crafted "buddyicon" command containing an excessively long "src" argument to a victim running an affected AIM client. The client application processes this command by attempting to copy the source URL into a predetermined buffer space, but due to the lack of proper bounds checking, the oversized input overflows the allocated memory region. This buffer overflow can overwrite adjacent memory locations including return addresses, function pointers, or other critical program state information, allowing an attacker to redirect program execution flow to malicious code that has been injected into the buffer or placed at a predictable memory location. The attack vector is particularly insidious because it requires no user interaction beyond receiving the malicious message, making it a classic example of a remote code execution vulnerability that can be exploited through social engineering or automated attack systems. The exploitation follows patterns consistent with the ATT&CK framework's T1059.007 technique for command and scripting interpreter, as the successful overflow enables arbitrary command execution on the target system. This vulnerability demonstrates how legacy instant messaging protocols and their implementations often lacked sufficient security considerations for handling untrusted input from network peers.
The operational impact of CVE-2000-1094 was significant given the widespread adoption of AOL Instant Messenger during its peak years, with millions of users potentially vulnerable to exploitation. When successfully exploited, this vulnerability could allow remote attackers to gain complete control over affected systems, enabling them to install malware, steal user credentials, access sensitive data, or use the compromised machine as a launching point for further attacks within a network. The vulnerability's impact extended beyond individual user compromise to potential network-level exploitation, as compromised AIM clients could serve as entry points for broader security breaches. Organizations using AIM in enterprise environments faced particular risk since the application often ran with elevated privileges and had access to sensitive corporate communication channels. The vulnerability also highlighted the importance of proper input validation and memory management practices in client-side applications, particularly those handling network data from untrusted sources. Security researchers and system administrators had to implement immediate patches or workarounds to protect their networks, emphasizing the critical need for regular security updates and vulnerability management processes. This particular vulnerability exemplifies the types of security flaws that were common in legacy software implementations and underscores why modern software development practices emphasize security by design principles and comprehensive testing for memory safety issues. The vulnerability's resolution required the development of proper bounds checking mechanisms and input validation routines that became standard practices in subsequent software development cycles, influencing how developers approach security considerations in networked applications.