CVE-2011-4363 in Proc::ProcessTable
Summary
by MITRE
ProcessTable.pm in the Proc::ProcessTable module 0.45 for Perl, when TTY information caching is enabled, allows local users to overwrite arbitrary files via a symlink attack on /tmp/TTYDEVS.
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Analysis
by VulDB Data Team • 12/14/2021
The vulnerability identified as CVE-2011-4363 resides within the Proc::ProcessTable Perl module version 0.45, specifically affecting systems where TTY information caching is enabled. This flaw represents a classic symlink attack scenario that exploits insecure temporary file handling mechanisms. The module creates temporary files in the /tmp directory to cache TTY device information, but fails to properly validate the existence and ownership of these temporary files before writing to them. When TTY caching is enabled, the ProcessTable.pm component attempts to write device information to /tmp/TTYDEVS without sufficient security checks, creating a window of opportunity for local attackers to manipulate the system's file creation process through symbolic link manipulation.
The technical execution of this vulnerability involves a race condition where an attacker can create a symbolic link at /tmp/TTYDEVS pointing to a target file they wish to overwrite, before the legitimate process creates the temporary file. This type of attack falls under the category of insecure temporary file handling as defined by CWE-377, specifically CWE-378 which addresses the creation of temporary files with insecure permissions and inadequate validation. The vulnerability operates at the privilege level of the user running the Perl process, making it particularly dangerous in multi-user environments where local privilege escalation opportunities exist.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can potentially allow attackers to modify critical system files or configuration data that the Proc::ProcessTable module might be processing. Attackers could leverage this to inject malicious content into system logs, modify authentication-related files, or corrupt important data structures that the module manages. The vulnerability is particularly concerning in environments where the Proc::ProcessTable module is used with elevated privileges or in system monitoring contexts where such modules might be invoked by privileged processes. This aligns with ATT&CK technique T1059.007 for execution through scripting and T1068 for privilege escalation through local exploitation.
Mitigation strategies for CVE-2011-4363 should focus on immediate patching of the Proc::ProcessTable module to version 0.46 or later, which contains the necessary security fixes for temporary file handling. System administrators should also implement restrictive permissions on the /tmp directory to prevent unauthorized symlink creation and consider disabling TTY information caching if the functionality is not essential for system operations. Additionally, monitoring for suspicious file creation patterns in /tmp and implementing proper file validation mechanisms can help detect and prevent exploitation attempts. The vulnerability demonstrates the importance of proper temporary file handling practices and aligns with security best practices outlined in NIST SP 800-125 for secure coding practices in Perl applications. Organizations should also review their systems for similar patterns of insecure temporary file usage and implement comprehensive security testing procedures to identify and remediate such vulnerabilities before they can be exploited by malicious actors.