CVE-2011-2765 in Pyro
Summary
by MITRE
pyro before 3.15 unsafely handles pid files in temporary directory locations and opening the pid file as root. An attacker can use this flaw to overwrite arbitrary files via symlinks.
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2011-2765 affects pyro versions prior to 3.15 and represents a critical security flaw in how the software manages process identifier files within temporary directories. This issue stems from improper handling of pid file creation and access permissions, creating a significant attack surface that can be exploited by malicious actors. The vulnerability specifically manifests when pyro creates pid files in temporary directory locations and opens these files with root privileges, establishing a dangerous privilege escalation vector.
The technical exploitation of this vulnerability relies on symbolic link manipulation within the temporary directory space where pyro stores its pid files. When pyro creates a pid file in a temporary location and opens it with elevated privileges, an attacker can create malicious symbolic links that point to arbitrary files on the system. This allows the attacker to write data to files that would normally be protected or restricted, effectively bypassing normal file access controls. The flaw operates under the principle of time-of-check to time-of-use vulnerabilities where the system checks file permissions at one point but the actual file operation occurs later, allowing for manipulation between these checks.
This vulnerability directly maps to CWE-59 and CWE-367 categories, representing weaknesses in file handling and time-of-check to time-of-use race conditions. The operational impact of this flaw is severe as it enables arbitrary file overwrite capabilities that can lead to complete system compromise. An attacker with access to the system can leverage this vulnerability to modify critical system files, inject malicious code into running processes, or manipulate the behavior of other applications that rely on the affected pid files. The root privilege escalation aspect makes this particularly dangerous as it allows attackers to bypass normal user access controls and gain elevated system privileges.
From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1059.001 for executing malicious code through command-line interfaces and T1548.001 for privilege escalation. The exploitation requires minimal prerequisites and can be automated, making it attractive to threat actors. The vulnerability affects systems where pyro is installed and running with elevated privileges, particularly in environments where temporary directories are world-writable or where users can create symbolic links in these locations. Organizations using pyro or similar software frameworks that handle pid files in temporary directories should consider this vulnerability as a critical threat requiring immediate remediation.
The recommended mitigations include upgrading to pyro version 3.15 or later where the pid file handling has been corrected to prevent symbolic link manipulation. Additionally, system administrators should ensure that temporary directories used by pyro have appropriate permissions and are not world-writable. Implementing proper file access controls and monitoring for unauthorized symbolic link creation in temporary directories can help detect potential exploitation attempts. The fix typically involves changing how pid files are created and accessed, ensuring that files are created with proper ownership and permissions, and avoiding the use of symbolic links in the pid file creation process.