CVE-2014-1639 in syncevolution
Summary
by MITRE
syncevo/installcheck-local.sh in syncevolution before 1.3.99.7 uses mktemp to create a safe temporary file but appends a suffix to the original filename and writes to this new filename, which allows local users to overwrite arbitrary files via a symlink attack on the new filename.
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Analysis
by VulDB Data Team • 02/01/2022
The vulnerability described in CVE-2014-1639 affects the syncevolution synchronization tool version 1.3.9.6 and earlier, specifically within the installcheck-local.sh script. This issue represents a classic symlink attack pattern that exploits improper temporary file handling mechanisms. The vulnerability stems from the script's use of mktemp command to create temporary files while simultaneously appending a suffix to the original filename, creating a scenario where an attacker can manipulate the file system to overwrite arbitrary files through symbolic link manipulation. The flaw exists in the script's approach to creating temporary files, where the original intention to use mktemp for safety is undermined by the subsequent filename manipulation that creates predictable paths vulnerable to symlink attacks.
The technical implementation of this vulnerability involves the interaction between mktemp functionality and the script's filename suffixing mechanism. When syncevolution processes files, it creates temporary files using mktemp but then modifies these filenames by appending suffixes, leading to a predictable temporary file path that attackers can target through symlink manipulation. The vulnerability operates under CWE-362, which classifies the issue as a race condition in temporary file handling, specifically involving improper temporary file creation and management. This pattern aligns with ATT&CK technique T1548.001, which covers privilege escalation through the exploitation of insecure file permissions and temporary file handling vulnerabilities.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it provides local attackers with the potential to escalate privileges and compromise the entire synchronization environment. Attackers can leverage this vulnerability to overwrite critical system files, configuration files, or even binary executables within the syncevolution framework, potentially leading to arbitrary code execution or complete system compromise. The attack requires local system access but can be particularly dangerous in environments where syncevolution runs with elevated privileges or where users have the ability to create symbolic links in temporary directories. This vulnerability affects systems where the syncevolution tool is installed and used for synchronization purposes, potentially exposing desktop environments, mobile devices, or server systems that rely on this synchronization framework.
Mitigation strategies for CVE-2014-1639 focus on both immediate patching and architectural improvements to temporary file handling. The primary solution involves updating to syncevolution version 1.3.9.7 or later, where the developers corrected the temporary file creation logic to eliminate the symlink attack surface. System administrators should also implement proper file system permissions and ensure that temporary directories are not writable by untrusted users. Additional protective measures include verifying that mktemp commands are used without subsequent filename manipulation, implementing proper sandboxing for synchronization tools, and monitoring for suspicious file system changes in temporary directories. Organizations should also consider implementing privilege separation techniques and ensuring that synchronization tools do not run with elevated privileges when possible. The vulnerability demonstrates the critical importance of proper temporary file handling in security-sensitive applications and highlights the need for comprehensive testing of file system interactions in security-critical code paths.