CVE-2010-4337 in gnash
Summary
by MITRE
The configure script in gnash 0.8.8 allows local users to overwrite arbitrary files via a symlink attack on the (1) /tmp/gnash-configure-errors.$$, (2) /tmp/gnash-configure-warnings.$$, or (3) /tmp/gnash-configure-recommended.$$ files.
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Analysis
by VulDB Data Team • 10/12/2021
The vulnerability identified as CVE-2010-4337 affects the gnash 0.8.8 multimedia framework and represents a classic symlink attack scenario that exploits insecure temporary file handling in the configure script. This issue resides in the software's build process where temporary files are created without proper security measures to prevent symbolic link manipulation by unauthorized users. The vulnerability specifically targets three temporary files that are created during the configuration phase of gnash installation, making it a pre-authentication local privilege escalation vector that can be exploited by any local user with access to the system.
The technical flaw manifests through the insecure creation of temporary files using predictable naming patterns that include process identifiers. When the configure script runs, it creates temporary files with names following the pattern /tmp/gnash-configure-errors.$$, /tmp/gnash-configure-warnings.$$, and /tmp/gnash-configure-recommended.$$ where $$ represents the process ID. This predictable naming scheme combined with the lack of proper file creation checks makes these files susceptible to symlink attacks. An attacker can create symbolic links with these exact names before the configure script executes, causing the script to write data to locations controlled by the attacker rather than the intended temporary files, potentially leading to arbitrary file overwrites.
The operational impact of this vulnerability extends beyond simple file overwrite capabilities as it can be leveraged for more sophisticated attacks within the local environment. Local users who can execute the gnash configure script can exploit this weakness to overwrite critical system files or inject malicious content into the build process. This vulnerability aligns with CWE-367, which describes Time-of-Check to Time-of-Use (TOCTOU) flaws, where the security check occurs at a different time than when the resource is actually accessed. The attack vector can be particularly dangerous in multi-user environments where attackers might target system files or configuration data that gets processed during gnash installation or update procedures.
From an attack framework perspective, this vulnerability maps to multiple ATT&CK techniques including T1068, which covers local privilege escalation through insecure file permissions, and T1059, covering execution through command-line interfaces where the configure script serves as the execution vehicle. The vulnerability also intersects with T1078, representing valid accounts and the ability to manipulate system configurations through legitimate installation processes. Security professionals should note that this issue demonstrates the importance of proper temporary file handling and the principle of least privilege in build environments, as the vulnerability can be exploited by any local user without requiring special permissions or network access.
Mitigation strategies should focus on implementing secure temporary file creation practices that prevent symlink attacks, including using secure file creation functions that check for existing symbolic links, implementing proper file permissions for temporary directories, and utilizing secure temporary file libraries. Organizations should also consider implementing automated patch management processes to ensure that vulnerable versions of gnash are not deployed in production environments. The fix typically involves modifying the configure script to use secure temporary file creation methods such as mkstemp or similar functions that guarantee atomic file creation without symbolic link vulnerabilities. Additionally, system administrators should monitor for unauthorized modifications to build directories and implement proper access controls to limit who can execute installation scripts on systems where gnash or similar software may be installed.