CVE-2007-0909 in PHP
Summary
by MITRE
Multiple format string vulnerabilities in PHP before 5.2.1 might allow attackers to execute arbitrary code via format string specifiers to (1) all of the *print functions on 64-bit systems, and (2) the odbc_result_all function.
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Analysis
by VulDB Data Team • 07/15/2019
The vulnerability identified as CVE-2007-0909 represents a critical format string vulnerability affecting PHP versions prior to 5.2.1, specifically targeting the core printf family of functions and the odbc_result_all function. This flaw exists in the manner PHP processes format strings, creating opportunities for attackers to manipulate memory access patterns and potentially execute arbitrary code on vulnerable systems. The vulnerability manifests differently across architectures, with particular severity on 64-bit systems where the *print functions become susceptible to exploitation. Format string vulnerabilities occur when application code fails to properly validate or sanitize user input that contains format specifiers, allowing attackers to craft malicious input that can manipulate the program's execution flow.
The technical exploitation of this vulnerability leverages the fundamental behavior of format string functions in C-based languages, where format specifiers such as %s, %d, and %x are used to control output formatting. When PHP's *print functions encounter untrusted input containing these specifiers, the application may interpret them as instructions for reading from memory locations, potentially leading to information disclosure or code execution. On 64-bit systems, the vulnerability becomes more pronounced due to differences in memory addressing and stack layout, amplifying the potential impact of malformed format strings. The odbc_result_all function presents an additional attack surface where user-controlled data can be processed through format string mechanisms, extending the scope of potential exploitation beyond standard output functions.
The operational impact of CVE-2007-0909 extends beyond simple code execution, encompassing data integrity breaches and system compromise. Attackers can exploit these vulnerabilities to read sensitive memory locations, potentially extracting database credentials, session tokens, or other confidential information from the application's memory space. The ability to execute arbitrary code through format string manipulation places vulnerable PHP applications at significant risk of full system compromise, particularly when applications process user input through these affected functions. This vulnerability directly aligns with CWE-134, which describes the weakness of using user-supplied format strings in printf-like functions without proper validation, making it a prime target for exploitation within the ATT&CK framework under the technique of command and control through format string vulnerabilities.
Mitigation strategies for this vulnerability require immediate patching of affected PHP installations to version 5.2.1 or later, where the format string handling has been properly addressed. System administrators should implement input validation measures to sanitize all user-supplied data before processing through printf-family functions, ensuring that format specifiers are properly escaped or removed. The principle of least privilege should be enforced by limiting the execution permissions of PHP processes and implementing proper memory protection mechanisms such as stack canaries and address space layout randomization. Additionally, monitoring and logging of format string related function calls can help detect potential exploitation attempts, while regular security audits should verify that no custom code introduces similar vulnerabilities through improper format string handling. Organizations should also consider implementing web application firewalls that can detect and block malicious format string patterns in HTTP requests, providing an additional layer of defense against this class of vulnerability.