CVE-2006-0200 in PHP
Summary
by MITRE
Format string vulnerability in the error-reporting feature in the mysqli extension in PHP 5.1.0 and 5.1.1 might allow remote attackers to execute arbitrary code via format string specifiers in MySQL error messages.
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Analysis
by VulDB Data Team • 03/12/2021
The vulnerability described in CVE-2006-0200 represents a critical format string flaw within PHP's mysqli extension that emerged in versions 5.1.0 and 5.1.1. This issue specifically targets the error-reporting functionality of the MySQLi extension, creating a pathway for remote attackers to exploit the system through carefully crafted MySQL error messages containing format string specifiers. The flaw operates at the intersection of database communication and string handling within PHP's extension architecture, making it particularly dangerous as it leverages legitimate database error reporting mechanisms to execute malicious code.
The technical implementation of this vulnerability stems from improper handling of format strings in the error-reporting code path of the mysqli extension. When MySQL generates error messages that contain format specifiers such as %s, %d, or other printf-style formatting elements, the PHP mysqli extension fails to properly sanitize or escape these strings before processing them. This creates a classic format string vulnerability where attacker-controlled data from database errors can be interpreted as format specifiers, allowing for memory corruption and arbitrary code execution. The vulnerability aligns with CWE-134 which specifically addresses the use of format strings with user-controlled data, and it maps to ATT&CK technique T1059.007 for remote code execution through application vulnerabilities.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with potential access to the underlying system running the PHP application. An attacker can leverage this flaw by crafting malicious database queries that trigger specific error conditions, causing the format string vulnerability to be exploited. The attack vector is particularly insidious because it requires no direct interaction with the application's input handling, instead exploiting the natural error reporting flow of database connections. This means that even applications that properly validate user input could be compromised through database error messages, making the attack surface significantly broader than typical input validation flaws. The vulnerability affects systems where PHP applications connect to MySQL databases using the mysqli extension, particularly in web environments where database interactions are common.
Mitigation strategies for this vulnerability require immediate patching of affected PHP versions to either 5.1.2 or later, which contained the necessary fixes to properly handle format strings in error reporting. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable systems, while monitoring for potential exploitation attempts through database connection patterns. The fix implemented by PHP developers involved proper sanitization of error messages before format string processing, ensuring that user-controlled data from database errors cannot be interpreted as format specifiers. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems running affected PHP versions and implement proper error handling practices that prevent format string vulnerabilities in custom extensions or applications. This vulnerability serves as a reminder of the importance of proper input validation and the critical need to address format string vulnerabilities in database interaction components.