CVE-2018-6791 in Plasma Workspace
Summary
by MITRE
An issue was discovered in soliduiserver/deviceserviceaction.cpp in KDE Plasma Workspace before 5.12.0. When a vfat thumbdrive that contains `` or $() in its volume label is plugged in and mounted through the device notifier, it's interpreted as a shell command, leading to a possibility of arbitrary command execution. An example of an offending volume label is "$(touch b)" -- this will create a file called b in the home folder.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability identified as CVE-2018-6791 represents a critical command injection flaw within the KDE Plasma Workspace device management system. This security issue exists in the soliduiserver/deviceserviceaction.cpp component and affects versions prior to 5.12.0, making it a significant concern for users of the KDE desktop environment who rely on automatic device mounting functionality. The flaw specifically manifests when handling removable storage devices with specially crafted volume labels that contain shell metacharacters, creating a dangerous intersection between device naming conventions and shell command interpretation.
The technical exploitation of this vulnerability occurs through a combination of improper input validation and unsafe shell command execution. When a user plugs in a vfat formatted thumbdrive containing volume labels with characters such as parentheses and dollar signs, the system fails to properly sanitize these identifiers before using them in shell contexts. The specific example "$(touch b)" demonstrates how the system interprets the volume label as a shell command rather than a simple device identifier, executing arbitrary commands with the privileges of the user running the device notifier service. This represents a classic command injection vulnerability that allows attackers to execute arbitrary code on the target system.
From an operational perspective, this vulnerability presents a severe threat to system security as it enables remote code execution through physical access or social engineering attacks. An attacker could craft malicious volume labels that execute harmful commands when plugged into a victim's system, potentially leading to privilege escalation, data exfiltration, or system compromise. The attack vector is particularly dangerous because it requires minimal user interaction beyond plugging in the device, making it an attractive target for attackers who can obtain physical access to target systems or convince users to mount malicious storage devices. This vulnerability directly relates to CWE-78 which defines improper neutralization of special elements used in OS commands, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter.
The mitigation strategy for this vulnerability involves upgrading to KDE Plasma Workspace version 5.12.0 or later, where proper input sanitization has been implemented to prevent shell command interpretation of volume labels. System administrators should also consider implementing additional security measures such as disabling automatic mounting of removable devices, enforcing strict device policy controls, and monitoring for suspicious device connections. Organizations should conduct security assessments to identify systems running vulnerable versions and implement patch management procedures to ensure timely remediation. The fix implemented in the newer versions demonstrates proper input validation techniques that prevent the dangerous interpretation of user-supplied data as executable shell commands, aligning with industry best practices for preventing command injection vulnerabilities.