CVE-2011-2199 in tftp-hpa
Summary
by MITRE
Buffer overflow in tftp-hpa before 5.1 allows remote attackers to cause a denial of service and possibly execute arbitrary code via the utimeout option.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2011-2199 represents a critical buffer overflow flaw within the tftp-hpa package version 5.0 and earlier, which exposes systems to potential remote exploitation. This vulnerability specifically affects the handling of the utimeout option during tftp client operations, creating a scenario where malicious actors can manipulate input parameters to trigger memory corruption. The flaw exists in the client-side implementation of the Trivial File Transfer Protocol (TFTP) utility, which is commonly used for network booting and firmware updates in embedded systems and network infrastructure devices.
The technical implementation of this vulnerability stems from inadequate input validation and buffer management within the tftp-hpa client code. When processing the utimeout option, the application fails to properly bounds-check user-supplied input data, allowing an attacker to overflow a fixed-size buffer allocated on the stack. This buffer overflow condition creates opportunities for arbitrary code execution or denial of service depending on the specific memory corruption patterns. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of unsafe string handling in network applications.
From an operational impact perspective, this vulnerability poses significant risks to network infrastructure and embedded systems that rely on TFTP for file transfers. Attackers can leverage this flaw to remotely compromise systems by sending specially crafted TFTP requests containing malicious utimeout values. The potential for remote code execution makes this particularly dangerous in environments where TFTP clients run with elevated privileges or where systems are directly accessible from untrusted networks. The denial of service aspect can also be exploited to disrupt network operations, particularly in scenarios involving network booting, firmware updates, or automated system management processes.
The exploitation of this vulnerability typically follows a pattern where attackers craft malicious TFTP requests with oversized utimeout parameters that overflow the buffer and overwrite adjacent memory locations. This can lead to stack corruption that may result in execution flow redirection, allowing attackers to inject and execute malicious code within the context of the TFTP client process. The vulnerability is particularly concerning in enterprise environments where TFTP clients are automatically invoked during system boot processes or firmware updates, creating persistent attack vectors. Organizations should consider this vulnerability in their threat modeling and incident response planning, as it can facilitate broader network compromise when combined with other attack vectors.
Mitigation strategies for CVE-2011-2199 include immediate patching of affected tftp-hpa installations to version 5.1 or later, which contains the necessary buffer overflow protections. System administrators should also implement network segmentation to limit TFTP client access to trusted networks and consider disabling TFTP functionality when not required for specific operational needs. Additionally, monitoring network traffic for suspicious TFTP activity and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and memory safety practices in network utilities, aligning with ATT&CK technique T1210 for exploitation of remote services and T1068 for privilege escalation through vulnerable applications. Organizations should also consider implementing network access controls to restrict TFTP traffic to authorized systems and monitor for unusual patterns in TFTP client behavior that might indicate exploitation attempts.