CVE-2015-1382 in Privoxy
Summary
by MITRE
parsers.c in Privoxy before 3.0.23 allows remote attackers to cause a denial of service (invalid read and crash) via vectors related to an HTTP time header.
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Analysis
by VulDB Data Team • 04/12/2022
The vulnerability identified as CVE-2015-1382 affects Privoxy versions prior to 3.0.23 and resides within the parsers.c file which handles HTTP header parsing operations. This issue represents a classic buffer over-read condition that occurs when processing HTTP time headers, specifically related to the parsing of date and time values in HTTP protocol communications. The flaw manifests when Privoxy encounters malformed or unexpected time header values in HTTP requests or responses, leading to memory access violations that result in application instability. This vulnerability falls under the CWE-125 vulnerability category, which describes out-of-bounds read conditions where programs access memory locations beyond the boundaries of allocated buffers. The attack vector specifically targets the HTTP time header parsing functionality, making it particularly dangerous in proxy environments where Privoxy processes numerous HTTP transactions from various sources.
The technical execution of this vulnerability involves remote attackers sending crafted HTTP requests containing malformed time headers to a vulnerable Privoxy instance. When the parser attempts to process these invalid time values, it reads memory locations beyond the intended buffer boundaries, causing the application to crash or behave unpredictably. This invalid memory read operation can lead to a complete denial of service condition where the proxy service becomes unavailable to legitimate users. The vulnerability is particularly concerning because HTTP time headers are commonly encountered in web communications, making exploitation relatively straightforward. The crash occurs during the normal operation of the HTTP parser, meaning that even benign traffic could trigger the vulnerability if it contains malformed time headers, potentially allowing attackers to perform sustained denial of service attacks against Privoxy instances.
The operational impact of CVE-2015-1382 extends beyond simple service disruption as it affects the reliability and availability of privacy and security proxy services that depend on Privoxy. Organizations relying on Privoxy for content filtering, ad blocking, or privacy protection may experience unexpected service outages that compromise their security infrastructure. The vulnerability's remote nature means that attackers do not require local access or authentication to exploit the flaw, making it a significant concern for publicly accessible Privoxy instances. From an attacker perspective, this vulnerability aligns with the ATT&CK technique T1499.004 which covers network denial of service attacks, specifically targeting proxy services. The vulnerability can be exploited in conjunction with other attack vectors to create more complex compromise scenarios, particularly in environments where Privoxy is used as part of broader security infrastructures.
Mitigation strategies for CVE-2015-1382 primarily focus on upgrading to Privoxy version 3.0.23 or later, which contains the necessary patches to address the buffer over-read condition in the HTTP time header parser. Organizations should also implement network monitoring to detect unusual traffic patterns that might indicate exploitation attempts, particularly around HTTP time header parsing. Additional defensive measures include deploying intrusion detection systems that can identify malformed HTTP headers and implementing rate limiting to prevent exploitation through automated attacks. The vulnerability highlights the importance of proper input validation and boundary checking in network protocol parsers, as outlined in security best practices for secure coding. Organizations should also consider implementing redundant proxy services to maintain availability during patching operations, and establish incident response procedures specifically addressing proxy service disruptions caused by similar vulnerabilities. Regular security assessments of proxy infrastructure and adherence to security update schedules remain critical defensive measures against this class of vulnerabilities.