CVE-2003-1171 in HTTP Server
Summary
by MITRE
Heap-based buffer overflow in the sec_filter_out function in mod_security 1.7RC1 through 1.7.1 in Apache 2 allows remote attackers to execute arbitrary code via a server side script that sends a large amount of data.
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Analysis
by VulDB Data Team • 04/16/2019
The vulnerability described in CVE-2003-1171 represents a critical heap-based buffer overflow within the mod_security module for Apache web servers. This security flaw exists in versions 1.7RC1 through 1.7.1 of the mod_security module, specifically within the sec_filter_out function that handles output filtering operations. The vulnerability arises from inadequate input validation and memory management practices that fail to properly bounds-check data before writing it to heap-allocated memory regions. This particular implementation flaw enables attackers to manipulate memory layout through carefully crafted malicious input data that exceeds expected buffer boundaries.
The technical execution of this vulnerability occurs when a remote attacker crafts a server-side script that sends excessive data to the vulnerable Apache server running the affected mod_security module. The sec_filter_out function processes this data without proper size validation, allowing the attacker to overflow the allocated heap buffer and potentially overwrite adjacent memory locations. This memory corruption can lead to arbitrary code execution with the privileges of the Apache process, typically running as the web server user account. The heap-based nature of the overflow provides attackers with additional flexibility in memory manipulation compared to stack-based overflows, as heap memory layout is less predictable and can be manipulated more effectively through controlled input data.
From an operational impact perspective, this vulnerability creates a severe threat to web server security and system integrity. Successful exploitation can result in complete system compromise, allowing attackers to execute malicious code, establish backdoors, or escalate privileges to gain administrative control over the affected server. The vulnerability affects all systems running Apache web servers with the vulnerable mod_security module versions, making it particularly dangerous in environments where multiple web applications are hosted. The remote nature of the attack means that exploitation can occur from any network location without requiring physical access to the target system, significantly expanding the attack surface and potential impact.
Organizations should immediately implement mitigations including updating to mod_security versions 1.7.2 or later where this vulnerability has been patched, applying the official security patches provided by the mod_security development team, and implementing network-level restrictions to limit access to vulnerable systems. Additionally, deploying intrusion detection systems with signatures for this specific vulnerability can help detect exploitation attempts. The vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a significant risk under the ATT&CK framework's execution and privilege escalation tactics. Security teams should also consider implementing application-level firewalls and input validation mechanisms as additional protective layers to prevent similar vulnerabilities from being exploited in other components of the web application stack.