CVE-2002-0130 in efax
Summary
by MITRE
Buffer overflow in efax 0.9 and earlier, when installed setuid root, allows local users to execute arbitrary code via a long -x argument.
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Analysis
by VulDB Data Team • 06/06/2018
The vulnerability identified as CVE-2002-0130 represents a critical buffer overflow flaw in the efax fax utility version 0.9 and earlier. This issue occurs when efax is installed with setuid root permissions, creating a dangerous privilege escalation vector that can be exploited by local users. The efax program, designed for sending and receiving faxes through modem connections, contains a flaw in its argument parsing mechanism that fails to properly validate input length. When a user provides an excessively long argument to the -x option, the program's buffer handling routines overflow, potentially allowing attackers to overwrite adjacent memory locations and execute arbitrary code with root privileges.
The technical nature of this vulnerability stems from improper input validation within the efax application's command line argument processing. Specifically, the program does not implement adequate bounds checking when handling the -x argument, which is typically used to specify the fax number or other transmission parameters. This lack of input sanitization creates a classic buffer overflow condition where maliciously crafted input can overwrite the program's stack frame, potentially corrupting the return address and allowing an attacker to redirect program execution flow. The setuid root installation exacerbates this issue significantly, as the program runs with elevated privileges, enabling successful exploitation to achieve root access rather than merely local privilege escalation.
From an operational perspective, this vulnerability presents a severe security risk to systems running affected versions of efax. Local users who can execute the efax utility can leverage this flaw to gain root-level access to the system, potentially leading to complete compromise. The attack vector is relatively straightforward, requiring only local access and knowledge of the vulnerable command line argument structure. This makes the vulnerability particularly dangerous in multi-user environments where local access might be more easily obtained than remote access. The impact extends beyond immediate privilege escalation, as root access typically provides attackers with unrestricted system control, including the ability to install backdoors, modify system files, or exfiltrate sensitive data.
The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to privilege escalation. According to ATT&CK framework, this vulnerability maps to T1068, privilege escalation through local exploitation, and T1548.001, abuse of setuid binaries, which are commonly targeted by attackers seeking to elevate their system privileges. Organizations should immediately implement mitigations including updating to patched versions of efax, removing setuid permissions from the binary if not strictly necessary, and implementing proper input validation measures. System administrators should also consider monitoring for unusual execution patterns of setuid binaries and ensure that only authorized users have local access to systems running vulnerable software versions. The remediation process should include comprehensive system auditing to identify all instances of the vulnerable efax version and proper patch management to prevent future occurrences of similar vulnerabilities.