CVE-2018-14036 in AccountsService
Summary
by MITRE
Directory Traversal with ../ sequences occurs in AccountsService before 0.6.50 because of an insufficient path check in user_change_icon_file_authorized_cb() in user.c.
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Analysis
by VulDB Data Team • 04/09/2023
The vulnerability identified as CVE-2018-14036 represents a critical directory traversal flaw within the AccountsService component of Linux systems, specifically affecting versions prior to 0.6.50. This issue stems from inadequate input validation mechanisms that fail to properly sanitize user-provided paths, creating an exploitable condition that allows attackers to manipulate file access patterns through carefully crafted ../ sequences. The vulnerability resides within the user_change_icon_file_authorized_cb() function in the user.c source file, where path validation logic proves insufficient to prevent malicious path resolution attempts.
The technical implementation of this vulnerability demonstrates a classic path traversal attack vector where an attacker can manipulate the icon file change functionality to access arbitrary files on the system. When the AccountsService processes user icon changes, it fails to properly validate the input paths against a whitelist or perform adequate sanitization checks before executing file operations. This allows an attacker to traverse the directory structure and potentially access sensitive files that should remain protected, including system configuration files, user credentials, or other privileged resources. The flaw specifically manifests in the authorization callback mechanism that handles icon file modifications, making it particularly dangerous as it operates within a privileged context.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to escalate privileges and potentially execute arbitrary code within the context of the AccountsService process. This creates a significant risk for system integrity and confidentiality, particularly in environments where AccountsService runs with elevated privileges or where user icon changes are permitted without proper sandboxing. Attackers could leverage this vulnerability to read sensitive system files, modify user accounts, or potentially gain deeper access to the underlying operating system. The vulnerability affects systems where user account management services are actively running and where icon file modifications are permitted, making it relevant across various Linux distributions and desktop environments that utilize the AccountsService framework.
Mitigation strategies for CVE-2018-14036 primarily focus on upgrading to AccountsService version 0.6.50 or later, which includes the necessary path validation fixes. System administrators should also implement additional security measures such as restricting write permissions for icon files, implementing proper input validation at multiple layers, and applying principle of least privilege configurations for the AccountsService process. The vulnerability aligns with CWE-22 Directory Traversal and can be categorized under ATT&CK technique T1059 for executing malicious code through service manipulation. Organizations should conduct thorough security assessments to identify systems running vulnerable versions and ensure comprehensive patch management protocols are in place to prevent exploitation of similar path traversal vulnerabilities in other system components.