CVE-2006-0097 in PHP
Summary
by MITRE
Stack-based buffer overflow in the create_named_pipe function in libmysql.c in PHP 4.3.10 and 4.4.x before 4.4.3 for Windows allows attackers to execute arbitrary code via a long (1) arg_host or (2) arg_unix_socket argument, as demonstrated by a long named pipe variable in the host argument to the mysql_connect function.
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Analysis
by VulDB Data Team • 09/05/2019
The vulnerability described in CVE-2006-0097 represents a critical stack-based buffer overflow affecting PHP versions 4.3.10 and 4.4.x prior to 4.4.3 on Windows platforms. This flaw resides within the create_named_pipe function located in libmysql.c, which is part of PHP's MySQL extension. The vulnerability specifically targets the handling of named pipe connections when establishing database connections through the mysql_connect function, creating a potential pathway for remote code execution. The attack vector exploits two distinct parameters: arg_host and arg_unix_socket, both of which can trigger the buffer overflow when supplied with excessively long input strings. This type of vulnerability falls under CWE-121, which categorizes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations on the program stack. The impact is particularly severe on Windows systems where PHP's MySQL extension relies on named pipes for certain connection methods, making this vulnerability exploitable in environments where such connection patterns are used.
The technical implementation of this vulnerability demonstrates a classic stack overflow scenario where the application fails to properly validate the length of input parameters before copying them into fixed-size stack buffers. When attackers provide excessively long strings to either the host argument or the unix_socket argument in mysql_connect function calls, the create_named_pipe function in libmysql.c does not perform adequate bounds checking on the input data. This allows the input data to overflow the allocated stack buffer space, potentially overwriting the return address of the calling function and other critical stack variables. The attack is particularly effective because it leverages the Windows named pipe mechanism that PHP uses for database connectivity, making it a legitimate connection path that would not raise immediate suspicion. The vulnerability essentially allows an attacker to inject malicious code into the stack memory space, potentially enabling arbitrary code execution with the privileges of the PHP process running on the target system.
The operational impact of CVE-2006-0097 extends beyond simple remote code execution to encompass broader system compromise and data breach potential. Since PHP applications are commonly deployed on web servers handling sensitive data, successful exploitation could allow attackers to gain complete control over the affected server. The vulnerability affects a widely used version of PHP, making it particularly dangerous in production environments where legacy systems may not have been updated. Attackers could leverage this vulnerability to establish persistent access, escalate privileges, or use the compromised system as a launch point for further attacks within the network infrastructure. The exploitation requires minimal sophistication and can be automated, making it attractive to both skilled and less experienced attackers. This vulnerability also aligns with ATT&CK technique T1059.007, which covers command and scripting interpreter for execution, as successful exploitation would likely involve executing malicious code through the compromised PHP process. Additionally, the vulnerability demonstrates characteristics of T1068, which covers exploit for privilege escalation, since the attacker could potentially escalate from a web application user to system-level privileges.
Mitigation strategies for CVE-2006-0097 focus primarily on immediate patching and system hardening measures. The most effective approach involves upgrading to PHP versions 4.4.3 or later, which contain the necessary fixes for the buffer overflow vulnerability. Organizations should implement comprehensive patch management processes to ensure all PHP installations are updated promptly. Network segmentation and access controls should be enforced to limit exposure of PHP applications to untrusted networks, reducing the attack surface. Input validation should be implemented at multiple layers, including application-level validation of database connection parameters to prevent malformed input from reaching vulnerable functions. Additionally, implementing runtime protections such as stack canaries, address space layout randomization, and DEP/NX bit enforcement can provide additional defense-in-depth measures. Security monitoring should be enhanced to detect unusual database connection patterns or attempts to establish named pipe connections with unusually long parameters, providing early warning of potential exploitation attempts. The vulnerability also underscores the importance of following secure coding practices and conducting regular security reviews of legacy codebases to identify and remediate similar buffer overflow conditions that may exist in other parts of the application stack.