CVE-2010-1168 in Safe
Summary
by MITRE
The Safe (aka Safe.pm) module before 2.25 for Perl allows context-dependent attackers to bypass intended (1) Safe::reval and (2) Safe::rdo access restrictions, and inject and execute arbitrary code, via vectors involving implicitly called methods and implicitly blessed objects, as demonstrated by the (a) DESTROY and (b) AUTOLOAD methods, related to "automagic methods."
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Analysis
by VulDB Data Team • 12/08/2024
The vulnerability identified as CVE-2010-1168 affects the Safe module for Perl, a security mechanism designed to provide restricted execution environments for untrusted code. This flaw exists in versions prior to 2.25 and represents a critical bypass of intended access controls that undermines the core security model of the module. The vulnerability specifically targets the Safe::reval and Safe::rdo access restrictions that are fundamental to preventing unauthorized code execution within restricted contexts. The flaw enables attackers to exploit implicit method calls and implicitly blessed objects to circumvent the security boundaries that the Safe module is supposed to enforce.
The technical implementation of this vulnerability leverages Perl's "automagic methods" which are automatically invoked by the interpreter without explicit calls from the programmer. The primary attack vectors involve the DESTROY and AUTOLOAD methods, which are special Perl methods that get called automatically under specific conditions. When objects are implicitly blessed or when methods are invoked through the automatic method resolution mechanism, attackers can manipulate the execution flow to bypass the intended security restrictions. The vulnerability exploits the fact that these automagic methods can be triggered in contexts where the security restrictions are not properly enforced, allowing for arbitrary code injection and execution.
The operational impact of this vulnerability is severe as it completely undermines the security model of the Safe module, which is commonly used to execute untrusted code in a controlled environment. Attackers can leverage this flaw to execute arbitrary code with the privileges of the process running the vulnerable Safe module, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it operates in a context-dependent manner, meaning the attack can be tailored to specific execution scenarios where the implicit method calls occur. This makes detection and prevention more challenging as the attack may not be immediately obvious during normal operation, and the exploitation can occur through legitimate code paths that are normally considered safe.
Organizations using Perl applications that rely on the Safe module for code isolation should immediately upgrade to version 2.25 or later to remediate this vulnerability. The fix addresses the improper handling of implicitly called methods and ensures that automagic methods like DESTROY and AUTOLOAD do not bypass the intended access restrictions. Security practitioners should also consider implementing additional monitoring for unusual method invocation patterns and conduct thorough code reviews to identify potential exploitation vectors. This vulnerability aligns with CWE-242, which covers "Risk of Using Insecure Methods" and specifically addresses issues related to improper handling of automatic method invocation in restricted execution environments. From an ATT&CK perspective, this vulnerability maps to T1059.007 for "Command and Scripting Interpreter: Perl" and T1548.001 for "Abuse Elevation Control Mechanism: Setuid and Setgid" as it allows for privilege escalation through code injection. The vulnerability demonstrates a classic example of how implicit behaviors in programming languages can create security holes when not properly accounted for in security models.