CVE-2004-0733 in Ollydbg
Summary
by MITRE
Format string vulnerability in OllyDbg 1.10 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via format string specifiers that are directly provided to the OutputDebugString function call.
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Analysis
by VulDB Data Team • 09/06/2024
The vulnerability identified as CVE-2004-0733 represents a critical format string flaw within OllyDbg version 1.10, a widely used x86 debugger for Windows systems. This weakness specifically manifests when the debugger processes user-supplied input that contains format string specifiers, which are then directly passed to the OutputDebugString function without proper sanitization or validation. The flaw exists in the debugger's handling of debug output messages, creating a pathway for malicious actors to manipulate the execution flow of the application.
The technical implementation of this vulnerability stems from improper input validation within OllyDbg's debug message processing subsystem. When the debugger encounters formatted strings containing malicious specifiers such as %s, %x, or %n, it fails to properly sanitize these inputs before passing them to the Windows API function OutputDebugString. This function interprets the format specifiers directly, leading to potential stack corruption and memory access violations. The vulnerability operates under CWE-134, which specifically addresses the use of untrusted data in format string functions, making it a classic example of improper input validation in security-critical code paths.
From an operational perspective, this vulnerability presents significant risk to users who may inadvertently process malicious debug output from compromised applications or networks. Remote attackers can exploit this weakness by crafting specially formatted debug messages that trigger the vulnerable code path, resulting in immediate denial of service through application crashes or more severe exploitation leading to arbitrary code execution. The attack vector is particularly dangerous because it can be triggered through legitimate debugging scenarios, making detection and prevention challenging. According to ATT&CK framework, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1203 (Exploitation for Client Execution) as attackers can leverage the debugger's functionality to execute malicious payloads in the context of the debugging process.
The impact of exploitation extends beyond simple crashes, as the format string vulnerability can be leveraged to perform stack smashing attacks that may allow attackers to overwrite critical memory locations or even inject and execute arbitrary code with the privileges of the debugging process. This makes OllyDbg an attractive target for attackers seeking to compromise systems through debugging tools, particularly in environments where such tools are frequently used for application analysis or malware reverse engineering. The vulnerability's persistence across multiple debugging scenarios means that any user running OllyDbg 1.10 and processing untrusted debug output becomes a potential victim of this attack vector.
Mitigation strategies for CVE-2004-0733 must address both immediate remediation and long-term security practices. The most effective immediate solution involves upgrading to a patched version of OllyDbg or implementing proper input validation mechanisms that sanitize all user-supplied format strings before they are processed. Security practitioners should also implement network segmentation and access controls to limit exposure to potentially malicious debug output streams. Additionally, organizations should consider implementing application whitelisting policies that restrict the execution of debugging tools in production environments where they are not required. The vulnerability highlights the importance of secure coding practices and proper input validation, particularly in security tools that handle untrusted data, and serves as a reminder of the critical need for regular security updates and vulnerability assessments in debugging and analysis software.