CVE-2023-0568 in Secure Backup
Summary
by MITRE • 02/16/2023
In PHP 8.0.X before 8.0.28, 8.1.X before 8.1.16 and 8.2.X before 8.2.3, core path resolution function allocate buffer one byte too small. When resolving paths with lengths close to system MAXPATHLEN setting, this may lead to the byte after the allocated buffer being overwritten with NUL value, which might lead to unauthorized data access or modification.
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Analysis
by VulDB Data Team • 12/11/2024
The vulnerability identified as CVE-2023-0568 represents a critical buffer overflow flaw in PHP's core path resolution functionality affecting versions prior to specific patches. This issue stems from an incorrect buffer allocation calculation within PHP's internal path handling mechanisms, creating a condition where memory boundaries are exceeded by a single byte. The flaw manifests when PHP processes file paths that approach the system's maximum path length limit known as MAXPATHLEN, which varies across different operating systems but typically ranges from 1024 to 4096 bytes depending on the platform. The vulnerability falls under CWE-122, which categorizes heap-based buffer overflow conditions where insufficient space is allocated for data, and specifically relates to improper boundary checking in memory management operations.
When PHP encounters a path resolution operation with a length near the system's MAXPATHLEN threshold, the internal buffer allocation routine computes the required memory size incorrectly by allocating exactly one byte less than needed. This seemingly minor miscalculation creates a situation where the final byte of the allocated buffer receives a null termination character from subsequent memory operations, effectively overwriting adjacent memory locations. The impact extends beyond simple memory corruption as it can result in unpredictable behavior including potential information disclosure through memory leaks, or more seriously unauthorized data modification if attackers can manipulate the memory layout to overwrite critical data structures or function pointers. This vulnerability demonstrates the dangerous implications of seemingly minor arithmetic errors in systems programming, particularly in high-level interpreted languages where such low-level memory management details are abstracted from developers.
The operational impact of CVE-2023-0568 poses significant risks to web applications running affected PHP versions, especially those handling user-supplied file paths or operating in environments with strict path length limitations. Attackers could potentially exploit this vulnerability to bypass security controls by manipulating file system operations or to cause denial of service through memory corruption. The vulnerability's exploitation requires specific conditions related to path length and system configuration, but given PHP's widespread use in web applications, the potential attack surface remains substantial. This flaw aligns with ATT&CK technique T1059.007 which involves the use of scripting languages for execution, particularly in web application contexts where PHP's file handling functions are commonly utilized. The vulnerability's nature suggests it could be leveraged for privilege escalation or data integrity compromise in environments where PHP processes have elevated permissions.
System administrators and developers should prioritize immediate patching of affected PHP installations to prevent exploitation of this vulnerability. The recommended remediation involves upgrading to PHP versions 8.0.28, 8.1.16, or 8.2.3 respectively, which contain the necessary fixes for the buffer allocation calculation. Organizations should implement comprehensive testing procedures to validate patch deployment across their environments, particularly in production systems where PHP handles file operations with potentially malicious input. Additional mitigations include implementing proper input validation for file paths, monitoring for unusual file system access patterns, and applying web application firewalls that can detect and block suspicious path manipulation attempts. Security teams should also conduct vulnerability assessments to identify any custom PHP extensions or applications that might be vulnerable to similar buffer overflow conditions, as this flaw could indicate broader memory management issues within the application stack. The vulnerability serves as a reminder of the importance of rigorous code review processes for memory management operations, particularly in systems where resource constraints and boundary conditions can lead to exploitable conditions.