CVE-2011-2722 in Linux Imaging And Printing Project
Summary
by MITRE
The send_data_to_stdout function in prnt/hpijs/hpcupsfax.cpp in HP Linux Imaging and Printing (HPLIP) 3.x before 3.11.10 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/hpcupsfax.out temporary file.
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Analysis
by VulDB Data Team • 12/02/2021
The vulnerability identified as CVE-2011-2722 represents a critical file system security flaw within HP Linux Imaging and Printing (HPLIP) software version 3.x prior to 3.11.10. This issue manifests in the send_data_to_stdout function located within the prnt/hpijs/hpcupsfax.cpp source file, where improper handling of temporary file creation creates exploitable conditions for local privilege escalation and arbitrary file overwrite attacks. The flaw specifically targets the /tmp/hpcupsfax.out temporary file which serves as a critical component in the fax processing functionality of the HPLIP suite, making it a prime target for malicious local users seeking to manipulate system files.
The technical implementation of this vulnerability stems from a race condition and insecure temporary file creation pattern that violates fundamental security principles for temporary file handling in Unix-like systems. When the send_data_to_stdout function executes, it creates a temporary file in the /tmp directory without proper security measures to prevent symbolic link attacks. An attacker can exploit this by creating a symbolic link with the name /tmp/hpcupsfax.out that points to a target file of their choice before the legitimate program creates the temporary file. This allows the attacker to overwrite any file that the HPLIP process has permissions to modify, potentially leading to privilege escalation, data corruption, or system compromise. The vulnerability directly maps to CWE-377: Insecure Temporary File and CWE-378: Creation of Temporary File With Insecure Permissions, both of which are well-documented weaknesses in secure coding practices.
The operational impact of CVE-2011-2722 extends beyond simple file overwrite capabilities, as it provides attackers with potential paths to escalate privileges and compromise system integrity. Local users who can execute the HPLIP fax functionality can leverage this vulnerability to modify critical system files, configuration files, or even binaries that the HPLIP process might have elevated permissions to access. This creates a significant risk for systems where HPLIP is installed with elevated privileges or where local users might have access to fax printing capabilities. The attack vector is particularly concerning in multi-user environments where users might not have direct administrative access but could still exploit this vulnerability to gain unauthorized access to system resources. The vulnerability also aligns with several techniques documented in the MITRE ATT&CK framework under T1059 (Command and Scripting Interpreter) and T1068 (Local Port Forwarding), as successful exploitation could enable attackers to establish persistent access or further compromise the system.
Mitigation strategies for CVE-2011-2722 require both immediate patching and implementation of defensive coding practices. The primary solution involves updating to HPLIP version 3.11.10 or later, which includes proper temporary file handling mechanisms that prevent symbolic link attacks. Organizations should also implement restrictive file system permissions for temporary directories, ensuring that temporary files are created with proper ownership and permissions that prevent symbolic link creation attacks. Additionally, system administrators should consider implementing mandatory access controls or file system integrity monitoring to detect unauthorized file modifications. The vulnerability highlights the importance of following secure coding guidelines, particularly those related to temporary file handling, and demonstrates the necessity of implementing proper input validation and file system security measures in all software components that interact with temporary files. Security teams should also conduct regular vulnerability assessments to identify similar insecure temporary file creation patterns within their software ecosystems and ensure that all system components follow established security standards for temporary file management.