CVE-2004-1698 in Popmessenger
Summary
by MITRE
The Base64 function in PopMessenger 1.60 (before 20 Sep 2004) and earlier allows remote attackers to cause a denial of service (application crash) via invalid characters in a message, which causes several alert dialogs to be displayed and leads to a crash.
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Analysis
by VulDB Data Team • 08/03/2025
The vulnerability described in CVE-2004-1698 represents a classic buffer overflow and input validation issue affecting the PopMessenger messaging application. This flaw exists within the Base64 decoding function of PopMessenger versions 1.60 and earlier, which were released prior to September 20, 2004. The vulnerability manifests when the application processes malformed Base64 encoded messages containing invalid characters, leading to a cascade of system failures that ultimately result in application instability and complete crash. The issue stems from inadequate input sanitization and error handling mechanisms within the cryptographic decoding routine, which fails to properly validate the integrity of encoded data before processing.
The technical exploitation of this vulnerability occurs through the manipulation of Base64 encoded message content, where attackers inject invalid characters that fall outside the standard Base64 character set. When the vulnerable PopMessenger application attempts to decode such malformed data, the Base64 function encounters unexpected input that it cannot properly handle, causing the application to enter an undefined state. This improper handling leads to the generation of multiple alert dialogs as the application attempts to report various internal errors, eventually overwhelming the system resources and causing the application to terminate abruptly. The vulnerability operates at the application level and does not require elevated privileges to exploit, making it particularly dangerous in environments where messaging applications are frequently used.
From an operational perspective, this vulnerability creates significant disruption in messaging environments where PopMessenger is deployed. The denial of service condition affects availability of the messaging service, potentially interrupting communication channels for users who rely on the application. The cascading effect of multiple alert dialogs can also impact system performance and user experience, as the application consumes excessive CPU cycles and memory resources during the crash sequence. This vulnerability represents a weakness in the application's defensive programming practices and highlights the importance of robust input validation and error handling mechanisms in security-critical applications. The issue falls under CWE-129, which addresses improper validation of array indices, and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
The recommended mitigation strategies for this vulnerability involve immediate patching of the PopMessenger application to a version that includes proper input validation and error handling for Base64 decoding operations. Organizations should implement network segmentation and access controls to limit exposure to this vulnerability, particularly in environments where the application is deployed. Additionally, implementing application-level monitoring and intrusion detection systems can help identify attempts to exploit this vulnerability through malformed message content. Regular security assessments and vulnerability scanning should be conducted to ensure that legacy applications are properly maintained and updated. The fix should include comprehensive input validation that rejects malformed Base64 characters before processing, along with graceful error handling that prevents application crashes and maintains system stability during error conditions.