CVE-2010-1861 in PHP
Summary
by MITRE
The sysvshm extension for PHP 5.2 through 5.2.13 and 5.3 through 5.3.2 allows context-dependent attackers to write to arbitrary memory addresses by using an object s __sleep function to interrupt an internal call to the shm_put_var function, which triggers access of a freed resource.
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Analysis
by VulDB Data Team • 09/13/2021
The vulnerability identified as CVE-2010-1861 represents a critical memory corruption flaw within the sysvshm extension of PHP versions 5.2 through 5.2.13 and 5.3 through 5.3.2. This issue stems from improper handling of shared memory operations during object serialization processes, creating a dangerous condition where attackers can manipulate memory access patterns to achieve arbitrary code execution. The vulnerability specifically targets the interaction between PHP's serialization mechanism and the sysvshm extension's internal memory management functions.
The technical root cause of this vulnerability lies in the improper handling of the __sleep magic method within PHP objects that utilize shared memory segments. When an object containing shared memory references enters the serialization process, the __sleep function can be invoked during an internal call to shm_put_var, which is responsible for storing variables in shared memory segments. This timing issue creates a window where the shared memory segment may be freed while still being accessed, leading to a use-after-free condition. The CWE-416 identifier applies here as the vulnerability involves accessing memory after it has been freed, while the CWE-787 classification covers the out-of-bounds write that occurs when attackers can manipulate memory addresses to write arbitrary data.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables context-dependent attackers to achieve arbitrary code execution on systems running vulnerable PHP versions. Attackers can leverage this flaw by crafting malicious objects that, when serialized and processed by the affected PHP applications, trigger the memory corruption condition. This allows for potential privilege escalation, data compromise, and system takeover scenarios. The vulnerability affects web applications that utilize shared memory operations through the sysvshm extension, making it particularly dangerous in environments where PHP applications handle untrusted input or process user data that could be manipulated to trigger the vulnerable code path.
Mitigation strategies for CVE-2010-1861 primarily focus on immediate version updates to patched PHP releases that address the memory handling issues within the sysvshm extension. Organizations should prioritize upgrading to PHP versions 5.2.14, 5.3.3, or later, where the underlying memory management has been corrected to prevent the use-after-free condition. Additionally, administrators should implement proper input validation and sanitization measures to prevent malicious object construction, while disabling the sysvshm extension when it is not required for application functionality. The ATT&CK framework's T1059.007 technique applies here as attackers may leverage this vulnerability to execute commands through compromised PHP applications. Security monitoring should include detection of unusual serialization patterns and memory access anomalies that could indicate exploitation attempts. System hardening measures such as disabling unnecessary PHP extensions, implementing proper access controls, and maintaining up-to-date security patches across all PHP installations remain essential defensive measures against this class of vulnerability.