CVE-2007-4335 in WinGate
Summary
by MITRE
Format string vulnerability in the SMTP server component in Qbik WinGate 5.x and 6.x before 6.2.2 allows remote attackers to cause a denial of service (service crash) via format string specifiers in certain unexpected commands, which trigger a crash during error logging.
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Analysis
by VulDB Data Team • 06/07/2025
The vulnerability identified as CVE-2007-4335 represents a critical format string vulnerability within the SMTP server component of Qbik WinGate versions 5.x and 6.x prior to 6.2.2. This flaw resides in the error logging mechanism of the mail server software and specifically affects the handling of malformed input commands. The vulnerability operates at the application level within the network service stack, where the SMTP server processes incoming commands and generates error messages for logging purposes. When an attacker sends specially crafted commands containing format string specifiers to the vulnerable SMTP service, the application fails to properly sanitize these inputs before using them in logging functions. This improper input handling creates a scenario where the format string vulnerability can be exploited to manipulate the program's execution flow.
The technical exploitation of this vulnerability occurs when the SMTP server component encounters unexpected commands that contain format specifiers such as %s, %d, or other printf-style formatting characters. These specifiers, when processed through the vulnerable logging functions, cause the application to interpret memory addresses or other unintended data as format strings, leading to memory corruption and ultimately resulting in a service crash. The vulnerability is classified as a classic format string vulnerability and aligns with CWE-134, which specifically addresses the use of format strings in applications without proper input validation. The flaw demonstrates poor input validation practices and inadequate sanitization of user-supplied data before processing within the application's logging subsystem.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack vectors. While the immediate effect is a denial of service condition that causes the WinGate SMTP service to crash and restart, the vulnerability could theoretically be leveraged by attackers to gain additional system information through memory dumping techniques. The service crash results in temporary unavailability of email services for legitimate users, which can cause significant business disruption in environments where email communication is critical. Organizations relying on WinGate for their email infrastructure would experience service interruptions that could affect productivity and potentially compromise business continuity. The vulnerability affects both major versions of the software, indicating it was present across a wide deployment base and required a specific patch to resolve.
Mitigation strategies for this vulnerability involve immediate application of the vendor-provided security patch that addresses the format string handling in the SMTP server component. System administrators should prioritize updating all affected WinGate installations to version 6.2.2 or later, as this release includes the necessary fixes to prevent the exploitation of the format string vulnerability. Network security measures should include implementing access controls to limit exposure of the SMTP service to trusted networks only, and monitoring for suspicious command patterns that might indicate exploitation attempts. Additionally, organizations should consider implementing intrusion detection systems that can identify malformed SMTP commands containing format specifiers, as this represents a specific attack pattern that can be detected through network traffic analysis. The vulnerability demonstrates the importance of proper input validation and the potential consequences of inadequate security testing in network service applications. This issue aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and reinforces the need for robust application security practices in critical infrastructure components.