CVE-2013-6809 in Tftpd32
Summary
by MITRE
Format string vulnerability in the client in Tftpd32 before 4.50 allows remote servers to cause a denial of service (crash) or possibly execute arbitrary code via format string specifiers in the Remote File field.
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Analysis
by VulDB Data Team • 12/23/2024
The vulnerability identified as CVE-2013-6809 represents a critical format string vulnerability within the Tftpd32 client component, specifically affecting versions prior to 4.50. This flaw exists in the handling of remote file requests where the client processes user-supplied format specifiers without proper validation or sanitization. The vulnerability manifests when a remote server crafts malicious format string sequences in the Remote File field, which are then processed by the vulnerable client application. Such format string vulnerabilities are particularly dangerous because they can lead to arbitrary code execution or system crashes depending on the specific exploitation vector and target environment.
The technical nature of this vulnerability aligns with CWE-134, which classifies format string vulnerabilities as weaknesses that occur when a program uses user-supplied data as a format string parameter to functions like printf, sprintf, or related functions. In the context of Tftpd32, the client application fails to properly validate the format specifiers present in the Remote File field, allowing attackers to inject malicious sequences that can manipulate the program's execution flow. When these format specifiers are processed, they can cause the application to read from or write to arbitrary memory locations, potentially leading to stack corruption, heap manipulation, or direct code execution.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to include potential remote code execution capabilities that could allow attackers to gain control over affected systems. The vulnerability affects Tftpd32 client implementations that process remote file requests, making it particularly dangerous in environments where users might interact with untrusted network servers. Attackers can exploit this vulnerability by setting up malicious TFTP servers that respond to client requests with crafted format string payloads, potentially leading to complete system compromise. The vulnerability's severity is amplified by its remote nature, as attackers do not require local access to exploit the flaw.
Mitigation strategies for CVE-2013-6809 should prioritize immediate patching of affected Tftpd32 installations to version 4.50 or later, which contains the necessary fixes for proper format string handling. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious TFTP servers, while monitoring network traffic for suspicious TFTP activity. Security measures should include validating all user input and implementing proper bounds checking when processing format strings, following the principles outlined in the ATT&CK framework's technique T1059.007 for command and scripting interpreter. Additionally, network administrators should consider disabling TFTP services when not required and implementing intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability.