CVE-2007-3009 in AppWeb HTTP Server
Summary
by MITRE
Format string vulnerability in the MprLogToFile::logEvent function in Mbedthis AppWeb 2.0.5-4, when the build supports logging but the configuration disables logging, allows remote attackers to cause a denial of service (daemon crash) via format string specifiers in the HTTP scheme, as demonstrated by a "GET %n://localhost:80/" request.
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Analysis
by VulDB Data Team • 01/24/2025
The vulnerability described in CVE-2007-3009 represents a critical format string vulnerability within the Mbedthis AppWeb 2.0.5-4 web server implementation. This flaw exists specifically within the MprLogToFile::logEvent function, which handles logging operations for the application web server. The vulnerability manifests when the software is compiled with logging capabilities but the logging feature is explicitly disabled through configuration settings. This creates a dangerous condition where the application continues to process format specifiers in user input even when logging is turned off, leading to potential exploitation by remote attackers. The vulnerability is particularly concerning because it affects the core logging functionality of the web server, which is typically expected to be a stable and secure component of the system architecture.
The technical exploitation of this vulnerability occurs through carefully crafted HTTP requests that contain format string specifiers within the scheme portion of the URL. The specific demonstration shows a request pattern of "GET %n://localhost:80/" where the %n format specifier is used to trigger the vulnerability. When the web server processes this malformed request, the format string vulnerability in the logEvent function allows the attacker to manipulate memory locations and potentially cause the daemon to crash. This type of vulnerability falls under CWE-134 which specifically addresses format string vulnerabilities where user-supplied data is used as a format string argument to functions like printf, sprintf, or fprintf. The exploitation technique leverages the fact that the application continues to process format specifiers even when logging is disabled, creating an execution path that bypasses normal input validation mechanisms.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise the stability and availability of the entire web server infrastructure. When the daemon crashes due to format string exploitation, it results in complete service disruption for legitimate users while also potentially exposing the system to further attacks. The vulnerability demonstrates poor input validation and memory management practices within the logging subsystem, where the application fails to properly sanitize user input before attempting to process it as a format string. This creates a dangerous scenario where an attacker can cause arbitrary code execution or memory corruption, depending on the specific implementation details and the target system architecture. The vulnerability also highlights the importance of proper code review and security testing, particularly for applications that handle user input in critical system components.
Mitigation strategies for CVE-2007-3009 should focus on immediate patching of the affected Mbedthis AppWeb versions, with priority given to upgrading to versions that have addressed this specific vulnerability. Organizations should implement network-level controls such as intrusion detection systems that can identify and block requests containing format string specifiers in URL schemes. Additionally, the application configuration should be reviewed to ensure that logging is properly managed and that any input validation is robust enough to prevent format string exploitation. Security best practices recommend implementing strict input sanitization, particularly for any data that might be used in printf-like functions, and following the principle of least privilege when configuring logging features. The vulnerability also underscores the importance of adhering to secure coding practices as outlined in the software security guidelines, particularly those related to format string handling and input validation. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communication, denial of service attacks, and privilege escalation through application exploitation, making it a significant concern for organizations that rely on embedded web servers for their infrastructure.