CVE-2003-0709 in Whois
Summary
by MITRE
Buffer overflow in the whois client, which is not setuid but is sometimes called from within CGI programs, may allow remote attackers to execute arbitrary code via a long command line option.
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Analysis
by VulDB Data Team • 04/20/2017
The vulnerability described in CVE-2003-0709 represents a critical buffer overflow condition within the whois client utility that exists in numerous Unix and Linux systems. This flaw occurs when the whois client processes command line arguments without proper bounds checking, allowing malicious input to overflow the allocated buffer space and potentially overwrite adjacent memory regions. The vulnerability is particularly concerning because the whois client is often invoked from within CGI programs, which are web-based scripts that can be accessed remotely over the internet, creating a direct pathway for remote code execution attacks.
The technical implementation of this vulnerability stems from improper input validation within the whois client's argument parsing mechanism. When the client receives command line options that exceed the predetermined buffer size, the excess data overflows into adjacent memory locations, potentially corrupting the stack frame or overwriting return addresses. This memory corruption can be exploited by attackers who craft malicious command line arguments that include shellcode or carefully constructed payload data designed to redirect program execution flow. The buffer overflow occurs at the command line argument processing level where the program fails to validate the length of input parameters before copying them into fixed-size buffers, a classic example of a CWE-121 buffer overflow vulnerability.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it provides attackers with the capability to execute arbitrary code on vulnerable systems with the privileges of the user running the whois client. Since the whois client is often invoked from CGI scripts, attackers can leverage web-based interfaces to trigger the vulnerable code path, potentially escalating privileges if the CGI program runs with elevated permissions. This vulnerability aligns with ATT&CK technique T1059.007 for command and script injection, as attackers can inject malicious command line arguments that get processed by the vulnerable whois client. The exploitability of this vulnerability is enhanced by the fact that whois clients are commonly available on Unix systems and often executed with sufficient privileges to allow code execution, making it a prime target for exploitation in web-based attack scenarios.
Mitigation strategies for CVE-2003-0709 should focus on both immediate patching and architectural improvements to prevent similar vulnerabilities in the future. System administrators should ensure that all whois client implementations are updated with proper bounds checking and input validation mechanisms that prevent buffer overflows from occurring. The implementation of stack canaries, address space layout randomization, and non-executable stack protections can provide additional layers of defense against exploitation attempts. Additionally, organizations should review their CGI program implementations to minimize the use of external utilities like whois that could be exploited through command line arguments, and implement proper input sanitization and validation at all points where external commands are invoked. The vulnerability demonstrates the importance of following secure coding practices and adhering to standards such as CWE-121 and CWE-78 to prevent buffer overflow conditions that can lead to privilege escalation and remote code execution attacks.