CVE-2007-4535 in Vavoom
Summary
by MITRE
The VStr::Resize function in str.cpp in Vavoom 1.24 and earlier allows remote attackers to cause a denial of service (daemon crash) via a string with a negative NewLen value within a certain UDP packet that triggers an assertion error.
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Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2007-4535 resides within the Vavoom 1.24 game engine and earlier versions, specifically within the VStr::Resize function located in the str.cpp source file. This flaw represents a classic buffer management issue that demonstrates poor input validation and error handling practices in networked applications. The vulnerability manifests when the game engine processes UDP packets containing malformed string data with negative length values, creating a scenario where the application fails to properly validate the NewLen parameter before attempting to resize string buffers.
The technical exploitation of this vulnerability occurs through the manipulation of UDP packet contents to include a negative value for the NewLen parameter within string operations. When the VStr::Resize function attempts to process this invalid parameter, it triggers an assertion error that causes the application daemon to crash and terminate unexpectedly. This assertion failure represents a fundamental breakdown in the application's error handling mechanisms, where the software fails to gracefully manage invalid input data rather than properly rejecting or sanitizing the malformed packet. The vulnerability operates at the core of the application's string handling capabilities, making it particularly dangerous as string operations are fundamental to almost all network communications and data processing within the game engine.
From an operational impact perspective, this vulnerability enables remote attackers to execute a denial of service attack against Vavoom servers and clients without requiring any authentication or privileged access. The daemon crash resulting from this attack effectively renders the affected system unavailable to legitimate users, disrupting gameplay and potentially causing service interruptions for multiplayer gaming sessions. The vulnerability's remote nature means that attackers can exploit it from anywhere on the network, making it particularly concerning for server administrators who must maintain continuous availability of their gaming services. The attack vector through UDP packets also means that the exploit can be delivered silently without requiring any interactive user engagement, making it difficult to detect and mitigate in real-time network monitoring systems.
This vulnerability aligns with CWE-129, which addresses improper validation of the length of input data, and demonstrates characteristics consistent with CWE-682, concerning computations that can generate values that are too large or too small for the intended representation. The flaw also relates to ATT&CK technique T1499.004, which covers network denial of service attacks through manipulation of application inputs. The assertion failure pattern indicates a lack of proper bounds checking and input sanitization, which are fundamental security practices recommended in secure coding standards such as those outlined in the CERT C Secure Coding Standard. Organizations should implement input validation mechanisms that explicitly check for negative values in length parameters and ensure that all buffer operations include proper bounds checking to prevent similar vulnerabilities from being exploited in other applications.
Mitigation strategies for this vulnerability include immediate patching of the Vavoom engine to version 1.25 or later, where the issue has been resolved through proper input validation and error handling. System administrators should also implement network-level filtering to restrict UDP packet processing and monitor for anomalous packet patterns that might indicate exploitation attempts. Additionally, application-level security measures such as input sanitization, assertion handling improvements, and robust error recovery mechanisms should be implemented to prevent similar issues from occurring in other software components. The vulnerability serves as a reminder of the critical importance of proper input validation in networked applications and the potential for seemingly minor flaws to result in significant service disruptions.