CVE-2017-14604 in Nautilus
Summary
by MITRE
GNOME Nautilus before 3.23.90 allows attackers to spoof a file type by using the .desktop file extension, as demonstrated by an attack in which a .desktop file's Name field ends in .pdf but this file's Exec field launches a malicious "sh -c" command. In other words, Nautilus provides no UI indication that a file actually has the potentially unsafe .desktop extension; instead, the UI only shows the .pdf extension. One (slightly) mitigating factor is that an attack requires the .desktop file to have execute permission. The solution is to ask the user to confirm that the file is supposed to be treated as a .desktop file, and then remember the user's answer in the metadata::trusted field.
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Analysis
by VulDB Data Team • 12/29/2022
The vulnerability identified as CVE-2017-14604 resides within GNOME Nautilus file manager version 3.23.90 and earlier, representing a sophisticated file type spoofing attack that exploits the trust placed in file extensions by the graphical user interface. This vulnerability falls under the category of CWE-20, which describes improper input validation, and specifically relates to CWE-347, concerning improper verification of cryptographic signatures, though in this case the issue stems from UI deception rather than cryptographic failure. The attack vector leverages the .desktop file extension which is traditionally used for creating application shortcuts in Linux desktop environments, but adversaries can manipulate this mechanism to disguise malicious payloads as benign file types such as PDF documents. The flaw demonstrates a critical failure in the principle of least privilege and user interface security design, where the system fails to properly distinguish between legitimate desktop entries and potentially maliciously crafted files that exploit the file manager's trust in extension-based file type identification.
The technical implementation of this vulnerability exploits the fundamental assumption that file managers can rely on extension-based file type detection for user interface presentation while maintaining appropriate security boundaries. When Nautilus encounters a .desktop file, it parses the file's metadata to determine how to display it in the user interface, specifically examining the Name field to determine the file's apparent type. In this attack scenario, an attacker creates a .desktop file where the Name field ends with .pdf, causing the file manager to display the file with a PDF icon and extension, while the Exec field contains a malicious shell command that executes when the file is opened. This creates a deceptive user experience where the interface misleadingly presents a potentially dangerous file as a safe document, bypassing the user's natural security instincts that would normally be triggered by executable file types. The vulnerability is particularly insidious because it requires the user to have execute permissions on the file, which aligns with the principle of least privilege and adds an additional layer of user interaction that must be overcome for successful exploitation.
The operational impact of this vulnerability extends beyond simple deception to represent a significant threat to user security and system integrity within the GNOME desktop environment. Attackers can leverage this vulnerability to bypass security mechanisms that rely on user interface cues for file type identification, potentially leading to successful social engineering attacks where users are tricked into executing malicious commands under the guise of legitimate documents. This attack pattern directly relates to ATT&CK technique T1059, which covers command and scripting interpreter execution, and demonstrates how user interface design flaws can be exploited to create attack vectors that circumvent traditional security controls. The vulnerability essentially creates a false sense of security for users who trust the visual representation provided by the file manager, potentially leading to privilege escalation or system compromise when users execute what they believe to be safe documents. The attack requires user interaction, which means that while the vulnerability is exploitable, it does not represent an automatic compromise, but rather requires social engineering or user manipulation to succeed.
The mitigation strategy for CVE-2017-14604 focuses on implementing proper user confirmation mechanisms and metadata-based trust management that aligns with security best practices for file type handling in graphical environments. The proposed solution requires the file manager to prompt users for explicit confirmation when encountering files with .desktop extensions, asking them to verify that the file should indeed be treated as a desktop entry rather than a regular file. This approach addresses the core issue by breaking the automatic trust relationship between file extension and perceived file type, requiring explicit user acknowledgment of potentially dangerous file types. The implementation of metadata::trusted field storage represents a sophisticated approach to maintaining user preferences while ensuring security, allowing users to make informed decisions about file handling and establishing a persistent security boundary. This mitigation strategy aligns with the principle of defense in depth and represents a user-centric approach to security that acknowledges the role of human factors in cybersecurity while maintaining technical controls. The solution effectively transforms a passive deception attack into an active security decision that requires user awareness and explicit consent, thereby reducing the attack surface and increasing overall system security.