CVE-2011-3204 in hammerhead
Summary
by MITRE
hammerhead.cc in Hammerhead 2.1.4 allows local users to write to arbitrary files via a symlink attack on (1) /tmp/hammer.log (aka the HH_LOG file) or (2) the REPORT_LOG file.
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Analysis
by VulDB Data Team • 02/10/2019
The vulnerability identified as CVE-2011-3204 resides within the hammerhead.cc component of Hammerhead version 2.1.4, representing a critical local privilege escalation and arbitrary file write flaw. This issue stems from insecure temporary file handling practices that create opportunities for malicious local users to manipulate system files through symbolic link attacks. The vulnerability specifically targets two designated temporary files: /tmp/hammer.log and the REPORT_LOG file, both of which are susceptible to symlink-based attacks that can be exploited by unauthorized local users to gain elevated privileges or corrupt system data.
The technical implementation of this vulnerability follows a classic symlink attack pattern where an attacker creates a symbolic link pointing to a target file that the vulnerable application would normally write to. When Hammerhead processes its logging operations, it follows the symbolic link and writes data to the target file rather than the intended temporary file. This flaw is classified under CWE-377 as "Insecure Temporary File" and specifically relates to CWE-378 which addresses "Creation of Temporary File With Insecure Permissions." The attack vector requires local system access and leverages the application's failure to properly validate temporary file paths before writing to them, making it a privilege escalation vulnerability that can be exploited by any local user with minimal privileges.
Operationally, this vulnerability poses significant risks to system integrity and security posture, particularly in multi-user environments where local privilege escalation can lead to unauthorized access to sensitive data or system manipulation. The impact extends beyond simple file corruption as attackers can potentially write to critical system files or configuration data, leading to persistent backdoors or complete system compromise. The vulnerability is particularly concerning because it operates at the local user level without requiring network access or specialized tools, making it easily exploitable in scenarios where attackers have gained low-privilege access to a system. The attack can be executed by creating a symbolic link in the /tmp directory that points to a file of the attacker's choice, then triggering the vulnerable logging functionality to write data to the target location.
Mitigation strategies for CVE-2011-3204 should focus on implementing secure temporary file handling practices that prevent symlink attacks. The recommended approach includes using secure temporary file creation functions that verify file ownership and permissions before writing, implementing proper file path validation, and avoiding the use of predictable temporary file names in world-writable directories like /tmp. Organizations should also consider implementing the principle of least privilege by restricting write access to temporary directories and ensuring that applications running with elevated privileges do not create or modify files in insecure locations. The vulnerability aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Python" and T1078.004 for "Valid Accounts: Cloud Accounts" when considering the broader exploitation landscape, though the specific attack requires local system access. System administrators should immediately patch affected systems, monitor for unauthorized file modifications, and implement proper file access controls to prevent exploitation of this and similar vulnerabilities.