CVE-2023-51698 in atril
Summary
by MITRE • 01/12/2024
Atril is a simple multi-page document viewer. Atril is vulnerable to a critical Command Injection Vulnerability. This vulnerability gives the attacker immediate access to the target system when the target user opens a crafted document or clicks on a crafted link/URL using a maliciously crafted CBT document which is a TAR archive. A patch is available at commit ce41df6.
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Analysis
by VulDB Data Team • 02/19/2025
The CVE-2023-51698 vulnerability affects Atril, a multi-page document viewer commonly used in Linux desktop environments, particularly within the MATE desktop environment. This document viewer is designed to handle various document formats including PDF, PostScript, and CBT files, which are essentially TAR archives containing structured document data. The vulnerability stems from insufficient input validation and sanitization when processing CBT documents, creating a critical command injection flaw that can be exploited by malicious actors. The vulnerability specifically manifests when the application processes a crafted CBT document that is actually a malicious TAR archive containing specially constructed files that trigger command execution during the document parsing process.
The technical flaw resides in how Atril handles the extraction and processing of files within TAR archives, particularly when these archives contain CBT documents. When a user opens a maliciously crafted CBT document, the application fails to properly sanitize file paths or content within the TAR archive, allowing attackers to inject arbitrary commands that execute with the privileges of the user running Atril. This command injection occurs during the document parsing phase when the application attempts to extract and process embedded files, creating an execution path where attacker-controlled input can be interpreted as shell commands. The vulnerability is classified as a command injection flaw under CWE-77 and represents a critical security weakness that bypasses normal access controls and privilege boundaries.
The operational impact of this vulnerability is severe and immediate, as it provides attackers with direct system access without requiring additional exploitation steps. When a target user opens the malicious document, the command injection occurs automatically, potentially allowing attackers to execute arbitrary code, escalate privileges, or gain complete control over the affected system. The attack vector is particularly dangerous because it requires only user interaction through normal document opening procedures, making it difficult to defend against through traditional network-based security measures. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, as it enables immediate system compromise through legitimate user actions. The vulnerability affects systems where Atril is installed and used for document viewing, particularly in desktop environments where users frequently open documents from untrusted sources.
Mitigation strategies for this vulnerability should include immediate application of the available patch from commit ce41df6, which addresses the input validation issues in CBT document processing. System administrators should also implement strict document handling policies, including disabling automatic document preview for untrusted files, using sandboxed environments for document viewing, and implementing network-level controls to prevent access to known malicious document repositories. Users should be educated about the risks of opening documents from untrusted sources and the importance of keeping their systems updated. Additional protective measures include implementing file type restrictions, using content filtering solutions, and monitoring for suspicious command execution patterns that might indicate exploitation attempts. Organizations should also consider implementing application whitelisting policies to restrict which document viewers can be executed on their systems, thereby reducing the attack surface for this and similar vulnerabilities.