CVE-2001-1498 in mod_bf
Summary
by MITRE
Buffer overflow in mod_bf 0.2 allows local users execute arbitrary commands via a long script.
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Analysis
by VulDB Data Team • 06/04/2018
The vulnerability identified as CVE-2001-1498 represents a critical buffer overflow flaw within the mod_bf Apache module version 0.2. This specific implementation weakness resides in the handling of script inputs within the web server's module architecture, creating a pathway for malicious exploitation. The mod_bf module, designed to provide bandwidth filtering capabilities, contains a fundamental design flaw that fails to properly validate input lengths before processing script commands. This oversight allows attackers to craft specially crafted inputs that exceed the allocated buffer space, leading to memory corruption and potential code execution. The vulnerability specifically affects systems where this module is installed and actively configured, making it particularly dangerous in environments where Apache web servers handle user-generated content or script execution requests.
The technical nature of this buffer overflow stems from improper input validation mechanisms within the mod_bf module's processing routines. When the module receives a script command, it does not adequately check the length of incoming data against predetermined buffer boundaries before copying the data into memory. This lack of bounds checking creates a classic buffer overflow condition where excess data overflows into adjacent memory locations, potentially overwriting critical program execution elements such as return addresses or function pointers. The vulnerability is classified as local privilege escalation since it requires an attacker to already have access to the system or a valid account with permissions to interact with the web server's script execution capabilities. This aligns with CWE-121, which categorizes buffer overflow conditions that occur when insufficient bounds checking is performed on buffers, and the vulnerability demonstrates characteristics consistent with CWE-787, which deals with out-of-bounds write conditions.
The operational impact of CVE-2001-1498 extends beyond simple code execution, as it provides attackers with the capability to gain unauthorized access to system resources and potentially escalate privileges. Local users who can submit malicious scripts through the vulnerable mod_bf module can leverage this weakness to execute arbitrary commands with the privileges of the web server process. This could result in complete system compromise, data exfiltration, or service disruption. The vulnerability's exploitation requires minimal sophistication and can be automated, making it particularly dangerous in production environments. The attack vector typically involves crafting a specially formatted script input that triggers the buffer overflow condition, allowing attackers to overwrite memory and redirect program execution flow. Organizations running affected Apache configurations are at significant risk, as the vulnerability can be exploited without requiring network-level access once local credentials are obtained. This vulnerability's impact is further amplified by the fact that it can be combined with other attack techniques to achieve persistent access or privilege escalation, making it a valuable target for threat actors.
Mitigation strategies for CVE-2001-1498 must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities. The primary recommendation involves upgrading to a patched version of the mod_bf module or removing the module entirely from affected systems. Organizations should conduct thorough inventory assessments to identify all systems running vulnerable Apache configurations and implement immediate patch management procedures. Additionally, system administrators should review and disable unnecessary modules to reduce the attack surface, particularly focusing on modules that handle user input or script execution. Implementing proper input validation and bounds checking mechanisms within web server configurations can help prevent similar issues from occurring in other modules. Security monitoring should be enhanced to detect unusual script execution patterns or attempts to exploit buffer overflow conditions. The vulnerability's characteristics align with ATT&CK technique T1059, which covers command and scripting interpreter usage, and T1068, which deals with exploit for privilege escalation. Regular security assessments and code reviews should be implemented to identify and address similar buffer overflow vulnerabilities in custom web server modules or third-party extensions. Organizations should also consider implementing network segmentation and access controls to limit local user privileges and reduce the potential impact of such vulnerabilities.