CVE-2008-1384 in PHP
Summary
by MITRE
Integer overflow in PHP 5.2.5 and earlier allows context-dependent attackers to cause a denial of service and possibly have unspecified other impact via a printf format parameter with a large width specifier, related to the php_sprintf_appendstring function in formatted_print.c and probably other functions for formatted strings (aka *printf functions).
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Analysis
by VulDB Data Team • 08/08/2019
The vulnerability described in CVE-2008-1384 represents a critical integer overflow condition within the PHP scripting language implementation that affects versions 5.2.5 and earlier. This flaw exists in the core string formatting functionality of PHP, specifically within the php_sprintf_appendstring function located in the formatted_print.c source file. The issue manifests when processing printf format parameters that contain excessively large width specifiers, creating a scenario where integer arithmetic operations exceed their defined boundaries and produce unexpected behavior. The vulnerability is classified as context-dependent because it requires specific conditions to be met for exploitation, typically involving crafted input that triggers the problematic formatting code path.
The technical implementation of this vulnerability stems from inadequate bounds checking within the PHP runtime's formatted string handling mechanisms. When a printf-style function encounters a format specifier with an unusually large width parameter, the internal integer calculations used to determine buffer sizes or string lengths can overflow, causing the system to allocate insufficient memory or produce incorrect string boundaries. This overflow condition can result in memory corruption, stack manipulation, or other undefined behaviors that fundamentally disrupt the normal execution flow of PHP applications. The vulnerability affects multiple printf-related functions throughout the PHP codebase, making it particularly dangerous as it can be triggered through various string formatting operations including sprintf, fprintf, and vprintf functions. According to CWE standards, this represents a classic integer overflow vulnerability classified under CWE-190, which specifically addresses integer overflow conditions that can lead to memory corruption and arbitrary code execution.
The operational impact of CVE-2008-1384 extends beyond simple denial of service conditions to potentially enable more sophisticated attacks. While the primary effect is a denial of service that can crash PHP processes or cause application instability, the underlying integer overflow creates opportunities for memory corruption that could be leveraged by attackers to execute arbitrary code. The vulnerability's exploitation potential is enhanced by the fact that it affects core formatting functions that are extensively used throughout PHP applications, making it possible for attackers to trigger the condition through user-supplied input that gets processed through printf-style functions. This makes the vulnerability particularly dangerous in web applications where user input is commonly processed through string formatting operations. The ATT&CK framework categorizes this vulnerability under privilege escalation and execution techniques, as successful exploitation could allow attackers to gain elevated privileges or execute malicious code within the PHP runtime environment.
Mitigation strategies for CVE-2008-1384 primarily focus on immediate version upgrades to PHP 5.2.6 or later, where the integer overflow conditions have been addressed through proper bounds checking and input validation. System administrators should implement comprehensive patch management procedures to ensure all PHP installations are updated to versions that contain the necessary security fixes. Additionally, input validation measures should be implemented at application boundaries to sanitize user-provided format strings before they are processed through printf functions. The implementation of proper error handling and memory management practices within PHP applications can help detect and prevent exploitation attempts. Organizations should also consider implementing network-based intrusion detection systems that can identify patterns associated with attempted exploitation of this vulnerability, particularly in web applications that process untrusted input through string formatting operations. Regular security assessments and code reviews focusing on string handling functions can help identify similar vulnerabilities in custom PHP applications that may not have been patched.