CVE-2002-0462 in Big Sam
Summary
by MITRE
bigsam_guestbook.php for Big Sam (Built-In Guestbook Stand-Alone Module) 1.1.08 and earlier allows remote attackers to cause a denial of service (CPU consumption) or obtain the absolute path of the web server via a displayBegin parameter with a very large number, which leaks the web path in an error message when PHP safe_mode is enabled, or consumes resources when safe_mode is not enabled.
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Analysis
by VulDB Data Team • 09/17/2025
The vulnerability identified as CVE-2002-0462 affects the bigsam_guestbook.php script within the Big Sam Built-In Guestbook Stand-Alone Module version 1.1.08 and earlier. This represents a classic input validation flaw that demonstrates poor handling of user-supplied parameters, specifically targeting the displayBegin parameter that controls pagination within the guestbook functionality. The vulnerability exists due to inadequate sanitization and bounds checking of integer parameters that should represent page offsets or record numbers in the guestbook display logic.
The technical implementation of this vulnerability stems from the script's failure to validate the magnitude of the displayBegin parameter before processing it. When attackers submit extremely large numerical values for this parameter, the application processes these inputs without proper bounds checking, leading to two distinct operational impacts. In environments where PHP safe_mode is enabled, the system reveals the absolute web server path through error messages generated during the processing of invalid parameters, creating a path disclosure vulnerability that falls under CWE-209. This path disclosure can provide attackers with critical information about the server's file structure, potentially enabling further attacks against the system's filesystem.
When PHP safe_mode is disabled, the same malformed input causes excessive CPU consumption as the application attempts to process the unrealistic pagination values, resulting in a denial of service condition. The system's resource exhaustion occurs because the guestbook script processes these large numbers through iterative loops or recursive operations that scale linearly with the input value, consuming significant processing cycles and potentially causing legitimate users to experience service degradation or complete unavailability.
This vulnerability aligns with several ATT&CK techniques including T1499.004 for Network Denial of Service and T1083 for File and Directory Discovery, as it enables both resource exhaustion attacks and path information leakage. The flaw represents a fundamental lack of input validation and error handling that violates security best practices for web application development. Organizations running affected versions of Big Sam should immediately apply the vendor-provided patch or upgrade to a newer version that implements proper parameter validation and bounds checking. Additionally, implementing input sanitization at the application level and configuring appropriate error handling to prevent information leakage would mitigate this vulnerability while maintaining system functionality. The vulnerability demonstrates how seemingly minor input validation gaps can create significant security risks when combined with improper error handling mechanisms.