CVE-2007-4635 in Yahoo!
Summary
by MITRE
Yahoo! Messenger 8.1.0.209 and 8.1.0.402 allows remote attackers to cause a denial of service (application crash) via certain file-transfer packets, possibly involving a buffer overflow, as demonstrated by ym8bug.exe. NOTE: this might be related to CVE-2007-4515. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 07/25/2019
The vulnerability described in CVE-2007-4635 represents a critical denial of service flaw affecting Yahoo! Messenger versions 8.1.0.209 and 8.1.0.402. This security issue manifests through malicious file-transfer packets that can trigger application crashes, effectively disrupting legitimate communication services. The vulnerability's classification as a potential buffer overflow indicates that attackers can exploit improperly handled data buffers during file transfer operations, leading to memory corruption that causes the application to terminate unexpectedly. The demonstration tool ym8bug.exe specifically illustrates how this vulnerability can be exploited in practice, suggesting that the flaw has been actively researched and documented by security researchers.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. In the context of Yahoo! Messenger's file transfer functionality, this could occur when the application fails to properly validate the size or content of incoming file transfer packets. The buffer overflow vulnerability creates an opportunity for remote code execution or system instability, though the current description focuses on denial of service as the primary impact. The connection to CVE-2007-4515 suggests this represents part of a broader class of vulnerabilities affecting the same software version, indicating potential systemic weaknesses in the application's input validation mechanisms.
Operationally, this vulnerability poses significant risks to users who rely on Yahoo Messenger is used for business purposes. Attackers could leverage this vulnerability to repeatedly crash the application, making it unusable for legitimate users and potentially disrupting business operations. The vulnerability's remote exploitability means that users are at risk even when simply receiving file transfer requests, as the malicious packet processing occurs during normal application operation.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected Yahoo! Messenger versions, as no reliable workarounds exist for the buffer overflow condition. Organizations should implement network monitoring to detect suspicious file transfer traffic patterns and consider temporary network segmentation to limit exposure. The vulnerability's characteristics align with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a classic example of how client-side applications can become attack vectors when proper input validation is absent. Security teams should also consider implementing application whitelisting policies to prevent execution of untrusted file transfer operations and maintain comprehensive logging of file transfer activities for incident response purposes.