CVE-2010-1862 in PHP
Summary
by MITRE
The chunk_split function in PHP 5.2 through 5.2.13 and 5.3 through 5.3.2 allows context-dependent attackers to obtain sensitive information (memory contents) by causing a userspace interruption of an internal function, related to the call time pass by reference feature.
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Analysis
by VulDB Data Team • 09/13/2021
The vulnerability identified as CVE-2010-1862 represents a critical information disclosure flaw within PHP's chunk_split function that affects versions 5.2 through 5.2.13 and 5.3 through 5.3.2. This issue stems from improper handling of memory structures during function execution, specifically when the call time pass by reference feature is utilized. The vulnerability operates through a sophisticated exploitation vector that leverages the interaction between PHP's internal memory management and user-space interruption mechanisms. Attackers can manipulate the execution flow to cause internal function interruptions that reveal sensitive memory contents, effectively exposing system information that should remain confidential.
The technical root cause of this vulnerability lies in the improper memory cleanup and handling within the chunk_split function when it encounters interruptions during execution. When PHP processes a chunk_split call with call time pass by reference enabled, the internal function state becomes vulnerable to manipulation through carefully crafted user input. This creates a condition where memory addresses and contents that should be protected are exposed to unauthorized access. The vulnerability manifests through a race condition or interruption scenario where the function's internal buffers are not properly secured against external interference, allowing attackers to read adjacent memory locations. This type of flaw falls under the CWE-200 category of "Information Exposure" and specifically relates to improper handling of memory structures during function execution.
The operational impact of CVE-2010-1862 extends beyond simple information disclosure, as the leaked memory contents could include sensitive data such as session tokens, database credentials, application configuration details, or other confidential information stored in memory. This vulnerability particularly affects web applications running on affected PHP versions, where the chunk_split function might be invoked with user-provided data. The exploitation requires context-dependent conditions, meaning attackers need to understand the specific execution environment and be able to trigger the exact sequence that causes the internal function interruption. This makes the vulnerability moderately difficult to exploit but highly dangerous when successfully executed, as it can provide attackers with valuable information for further attacks.
Mitigation strategies for this vulnerability primarily focus on immediate version upgrades to PHP 5.2.14 or 5.3.3, which contain the necessary patches to address the memory handling issues. System administrators should also consider disabling the call time pass by reference feature in php.ini configuration files, as this removes one of the attack vectors that enables the exploitation. Additionally, implementing proper input validation and sanitization can help reduce the risk of exploitation by preventing malicious data from reaching vulnerable functions. Organizations should conduct thorough security assessments of their PHP applications to identify any potential usage of the chunk_split function with user-provided data, and implement monitoring solutions to detect unusual memory access patterns that might indicate exploitation attempts. The vulnerability's classification under the ATT&CK framework would place it in the Information Gathering phase, specifically related to credential access and reconnaissance activities that precede more sophisticated attacks.