CVE-2005-3891 in Instant Messenger
Summary
by MITRE
Stack-based buffer overflow in Gadu-Gadu 7.20 allows remote attackers to cause a denial of service (crash) via an image filename between exactly 192 to 200 characters, which does not account for the "imgcache\" string that is added to the end of the buffer.
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Analysis
by VulDB Data Team • 06/24/2018
The vulnerability described in CVE-2005-3891 represents a classic stack-based buffer overflow affecting the Gadu-Gadu instant messaging client version 7.20. This flaw exists within the client's handling of image filenames during the caching process, creating a dangerous condition that can be exploited by remote attackers to crash the application. The vulnerability specifically manifests when processing image filenames that fall within a precise character range of exactly 192 to 200 characters, making it both predictable and exploitable.
The technical implementation of this vulnerability stems from improper input validation within the image caching mechanism of the Gadu-Gadu client. When an image filename is processed, the application prepends the string "imgcache\" to the beginning of the filename before storing it in a fixed-size stack buffer. This preprocessing step creates a critical miscalculation in buffer size estimation, as attackers can craft filenames that, when combined with the prepended string, exceed the allocated buffer space. The buffer overflow occurs because the application fails to account for the additional characters that will be added during the caching process, leading to memory corruption that ultimately results in application crash.
From an operational impact perspective, this vulnerability provides remote attackers with a reliable method to achieve denial of service against targeted Gadu-Gadu clients. The specific character range requirement makes this attack vector both precise and potentially automated, as attackers can easily craft malicious filenames that will consistently trigger the overflow condition. The vulnerability does not appear to enable arbitrary code execution, but the consistent crash behavior can be leveraged to disrupt service availability for legitimate users. This type of denial of service attack represents a significant concern for users who rely on the messaging client for business or personal communication, as it can be used to repeatedly disrupt their ability to communicate effectively.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which classifies this issue as a fundamental memory safety problem where data is written beyond the bounds of a stack buffer. This weakness is particularly dangerous because it can be exploited through network-based attacks without requiring local access, making it a prime target for attackers seeking to disrupt services. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 Network Denial of Service, where adversaries leverage software vulnerabilities to exhaust system resources or cause application instability. The predictable nature of the attack vector also aligns with T1059 Command and Scripting Interpreter, as attackers can craft specific payloads that will reliably trigger the vulnerable code path. Mitigation strategies should include immediate patch deployment, input validation improvements, and potentially network-based restrictions to prevent exploitation of this vulnerability in environments where patching may be delayed.
This vulnerability highlights the critical importance of proper buffer size calculations and input validation in client-side applications, particularly those handling user-provided data. The issue demonstrates how seemingly simple preprocessing operations can create dangerous buffer overflow conditions when not properly accounted for in security design. Organizations should implement comprehensive input sanitization measures and regular security assessments to identify similar vulnerabilities in their software systems. The vulnerability also underscores the need for robust error handling and memory management practices in instant messaging and communication applications that process external content, as these systems are particularly susceptible to exploitation through crafted user inputs.