CVE-2010-3065 in PHP
Summary
by MITRE
The default session serializer in PHP 5.2 through 5.2.13 and 5.3 through 5.3.2 does not properly handle the PS_UNDEF_MARKER marker, which allows context-dependent attackers to modify arbitrary session variables via a crafted session variable name.
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Analysis
by VulDB Data Team • 09/23/2021
The vulnerability identified as CVE-2010-3065 represents a critical session management flaw in PHP versions 5.2 through 5.2.13 and 5.3 through 5.3.2. This issue stems from the default session serializer's improper handling of the PS_UNDEF_MARKER marker, which creates a condition where attackers can manipulate session data through carefully crafted session variable names. The flaw exists within the serialization and deserialization process of PHP session data, specifically affecting how the system interprets undefined variable markers during session processing. This vulnerability demonstrates a classic case of improper input validation and handling within core PHP functionality, potentially allowing unauthorized modification of session state information.
The technical implementation of this vulnerability exploits the session serialization mechanism by leveraging the PS_UNDEF_MARKER constant which is used internally by PHP's session handling system. When PHP processes session data, it uses specific markers to indicate variable states, including undefined variables. The flaw occurs because the session deserializer does not properly validate or sanitize the PS_UNDEF_MARKER when processing user-supplied session variable names. Attackers can craft session variable names that contain this marker, causing the deserializer to incorrectly interpret subsequent session variables, leading to arbitrary session variable modification. This behavior creates a scenario where an attacker can effectively bypass normal session security controls and manipulate session data that should remain protected.
The operational impact of CVE-2010-3065 is substantial as it allows context-dependent attackers to modify arbitrary session variables, potentially leading to session hijacking, privilege escalation, or unauthorized access to protected resources. Since session variables often contain authentication tokens, user permissions, or other sensitive data, this vulnerability can be exploited to gain unauthorized access to user accounts or system resources. The attack requires minimal privileges and can be executed through manipulated session cookies or parameters, making it particularly dangerous in web applications where session management is critical. This vulnerability directly relates to CWE-20, which addresses improper input validation, and aligns with ATT&CK technique T1548.001 for privilege escalation through session manipulation.
Organizations affected by this vulnerability should immediately upgrade to PHP versions 5.2.14 or 5.3.3, which contain the necessary patches to address the PS_UNDEF_MARKER handling issue. The fix involves proper validation of session variable names during deserialization to prevent malicious markers from being processed as legitimate session data. System administrators should also implement comprehensive session management practices including secure session cookie configuration, regular session regeneration, and monitoring for unusual session activity. Additionally, organizations should conduct security assessments to identify any applications that may be vulnerable to this type of session manipulation attack and ensure proper input sanitization is implemented throughout their applications. The vulnerability serves as a reminder of the critical importance of secure session handling in web applications and the potential consequences of insufficient input validation in core language components.