CVE-2011-3616 in Conky
Summary
by MITRE
The getSkillname function in the eve module in Conky 1.8.1 and earlier allows local users to overwrite arbitrary files via a symlink attack on /tmp/.cesf.
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Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-3616 resides within the eve module of Conky version 1.8.1 and earlier, representing a significant security flaw that enables local attackers to execute arbitrary file overwrites through a carefully crafted symlink attack. This issue specifically targets the getSkillname function which operates on the temporary file path /tmp/.cesf, creating a dangerous privilege escalation vector for malicious users who possess local access to the system. The vulnerability demonstrates a classic race condition and insecure temporary file handling pattern that has been documented in numerous security advisories and represents a fundamental flaw in the software's file access methodology.
The technical implementation of this vulnerability stems from improper handling of temporary files within the application's runtime environment. When the getSkillname function executes, it creates or accesses the file /tmp/.cesf without adequate security measures to prevent symbolic link manipulation. Attackers can exploit this by creating a symbolic link at the targeted location that points to any writable file on the system, allowing them to overwrite critical system files or configuration data when the vulnerable application attempts to write to the temporary location. This type of attack falls under the category of insecure temporary file creation as defined by CWE-377, which specifically addresses the creation of temporary files with insecure permissions or predictable names. The flaw represents a direct violation of secure coding practices and demonstrates poor file system access control implementation.
The operational impact of this vulnerability extends beyond simple file corruption, as local users with minimal privileges can leverage this weakness to gain unauthorized access to system resources and potentially escalate their privileges within the local environment. The attack vector requires only local system access and the ability to create symbolic links, making it particularly dangerous in multi-user environments where privilege separation is expected. Successful exploitation could result in the modification of critical system files, configuration data, or even the installation of malicious code that persists across system reboots. This vulnerability directly impacts the integrity and confidentiality of system data, as attackers can manipulate the application's behavior by overwriting files that the application expects to be present at the specified location, potentially leading to privilege escalation or denial of service conditions.
Mitigation strategies for CVE-2011-3616 should focus on immediate patching of the Conky application to version 1.9.0 or later, where the vulnerable file handling logic has been corrected. System administrators should implement proper temporary file handling procedures including the use of secure temporary file creation functions that prevent symbolic link attacks through atomic file creation with appropriate permissions. The fix typically involves ensuring that temporary files are created with exclusive access modes and that the application validates the actual file path rather than following symbolic links. Additionally, system hardening measures such as restricting write permissions to the /tmp directory, implementing proper file system permissions, and using secure temporary file creation patterns as recommended by the posix standard should be enforced. Organizations should also consider implementing monitoring for unauthorized file modifications in the /tmp directory and conducting regular security audits to identify similar vulnerabilities in other applications that may be susceptible to the same class of attack as defined in the ATT&CK framework under T1059 for execution and T1070 for indicator removal.