CVE-2005-1857 in simpleproxy
Summary
by MITRE
Format string vulnerability in simpleproxy before 3.4 allows remote malicious HTTP proxies to execute arbitrary code via format string specifiers in a reply.
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Analysis
by VulDB Data Team • 11/22/2024
The vulnerability identified as CVE-2005-1857 represents a critical format string vulnerability within simpleproxy software versions prior to 3.4. This flaw exists in the proxy server's handling of HTTP responses from malicious upstream proxies, creating a path for remote code execution attacks. The vulnerability stems from improper input validation and sanitization when processing HTTP proxy responses that contain format string specifiers. Attackers can exploit this weakness by crafting malicious HTTP proxy replies that include format specifiers such as %s, %d, or %x, which the vulnerable proxy software fails to properly escape or validate before processing. This type of vulnerability falls under CWE-134 which specifically addresses the use of format strings without proper validation, making it a well-documented and dangerous class of software flaw.
The operational impact of this vulnerability extends beyond simple data corruption or application crashes, as it enables full remote code execution capabilities for attackers who can control malicious HTTP proxy servers. When simpleproxy processes a response containing malicious format specifiers, the software's string formatting functions interpret these specifiers as instructions for memory access patterns, potentially leading to stack corruption, information disclosure, or arbitrary code execution. The vulnerability is particularly concerning in proxy server environments where multiple clients may be routed through a single vulnerable instance, amplifying the potential attack surface. This flaw aligns with ATT&CK technique T1190 which describes the exploitation of vulnerabilities in proxy services to establish persistent access or execute malicious code within network environments.
The technical exploitation of CVE-2005-1857 requires an attacker to have control over an upstream HTTP proxy server or to be able to intercept and modify HTTP traffic between clients and the vulnerable proxy. Once successfully exploited, attackers can leverage the format string vulnerability to overwrite memory locations, inject malicious code, or gain elevated privileges within the proxy server's execution context. The vulnerability demonstrates a fundamental failure in input validation practices within the proxy software's HTTP response processing pipeline, where user-supplied data from upstream proxies is not properly sanitized before being passed to string formatting functions. Organizations using simpleproxy versions prior to 3.4 should immediately implement security patches or upgrades to mitigate this risk, as the vulnerability can be exploited remotely without authentication and can lead to complete compromise of the proxy server infrastructure. The fix typically involves implementing proper input validation and sanitization of HTTP proxy responses, ensuring that format specifiers are properly escaped or removed before processing, which aligns with defensive programming practices recommended in industry security standards.