CVE-2012-0807 in suhosin
Summary
by MITRE
Stack-based buffer overflow in the suhosin_encrypt_single_cookie function in the transparent cookie-encryption feature in the Suhosin extension before 0.9.33 for PHP, when suhosin.cookie.encrypt and suhosin.multiheader are enabled, might allow remote attackers to execute arbitrary code via a long string that is used in a Set-Cookie HTTP header.
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Analysis
by VulDB Data Team • 11/29/2021
The vulnerability described in CVE-2012-0807 represents a critical stack-based buffer overflow within the Suhosin PHP extension, specifically affecting versions prior to 0.9.33. This flaw exists in the suhosin_encrypt_single_cookie function which handles transparent cookie encryption, a security feature designed to protect sensitive cookie data from tampering and unauthorized access. The vulnerability becomes exploitable when both suhosin.cookie.encrypt and suhosin.multiheader configuration directives are enabled, creating a dangerous combination that transforms what should be a protective mechanism into a potential attack vector.
The technical implementation of this vulnerability stems from inadequate input validation within the cookie encryption process. When a Set-Cookie HTTP header contains an excessively long string, the suhosin_encrypt_single_cookie function fails to properly bounds-check the input data before copying it to a fixed-size stack buffer. This classic buffer overflow condition occurs because the function assumes a maximum string length that is insufficient for handling potentially maliciously crafted inputs. The overflow allows attackers to overwrite adjacent stack memory, potentially corrupting program execution flow and enabling arbitrary code execution. The vulnerability operates at the application layer and requires no special privileges beyond network access to exploit, making it particularly dangerous in web server environments.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally undermines the security posture of web applications using vulnerable Suhosin configurations. Attackers can leverage this flaw to gain complete control over affected web servers, potentially leading to data breaches, service disruption, and further lateral movement within compromised networks. The vulnerability's exploitation is particularly concerning because it can be triggered through standard HTTP cookie headers, making it accessible via routine web browsing activities. The combination of transparent cookie encryption being enabled alongside multiheader processing creates a perfect storm where legitimate security features become attack vectors. This flaw aligns with CWE-121, stack-based buffer overflow, and represents a significant concern for organizations running PHP applications with Suhosin extensions, as it bypasses traditional input validation mechanisms that should protect against such attacks.
Mitigation strategies for CVE-2012-0807 require immediate action to upgrade to Suhosin version 0.9.33 or later, which includes proper bounds checking and input validation mechanisms. Organizations should also consider disabling the problematic cookie encryption feature if it is not essential for their security requirements, particularly when multiheader processing is enabled. Network-level protections such as web application firewalls can provide additional defense-in-depth, though they cannot fully compensate for the underlying vulnerability. Security monitoring should focus on detecting unusual cookie header patterns that might indicate exploitation attempts, while system administrators should implement regular security assessments to identify other potentially vulnerable configurations. The ATT&CK framework categorizes this vulnerability under privilege escalation and code execution techniques, making it a critical target for defensive measures and incident response planning. Regular security updates and patch management processes become essential to prevent exploitation of similar vulnerabilities in the broader PHP ecosystem.