CVE-2020-0570: Qt Library Privilege Escalation Vulnerability

CVE-2020-0570 Overview

CVE-2020-0570 is an uncontrolled search path vulnerability affecting the Qt Library. This privilege escalation flaw exists in Qt versions before 5.14.0, 5.12.7, and 5.9.10, allowing an authenticated user with local access to potentially elevate their privileges on the affected system.

Critical Impact

An authenticated local attacker can exploit this uncontrolled search path vulnerability to achieve privilege escalation, potentially gaining elevated access to system resources and sensitive data.

Affected Products

• Qt Qt (versions before 5.14.0, 5.12.7, and 5.9.10)
• Red Hat Enterprise Linux 7.0
• Red Hat Enterprise Linux 8.0

Discovery Timeline

• 2020-09-14 - CVE-2020-0570 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-0570

Vulnerability Analysis

This vulnerability is classified under CWE-426 (Untrusted Search Path), which occurs when an application searches for executable files or libraries in directories that can be controlled by malicious actors. In the case of Qt Library, the application fails to properly validate or restrict the search path when loading libraries or executables, creating an opportunity for attackers to inject malicious code.

The local attack vector means an attacker must have some level of authenticated access to the target system. Once local access is established, the attacker can place a malicious library or executable in a location that Qt will search before the legitimate location. When the Qt-based application executes and attempts to load the expected library, it instead loads the attacker's malicious code with the privileges of the running application.

Root Cause

The root cause of CVE-2020-0570 is improper handling of search paths within the Qt Library. The application does not adequately restrict or validate the directories it searches when loading shared libraries or executables. This allows an attacker to introduce malicious code into a directory that appears earlier in the search order than the intended library location.

Attack Vector

The attack requires local access to the target system with an authenticated user account. The attacker must be able to write files to directories that are searched by Qt-based applications when loading libraries. The exploitation scenario typically involves:

1. Identifying a Qt-based application that loads libraries using an insecure search path
2. Placing a malicious library with the same name as a legitimate library in a directory that is searched first
3. Triggering the Qt application to load the malicious library, executing attacker-controlled code with the application's privileges

This privilege escalation technique is commonly known as DLL hijacking on Windows or shared library preloading on Linux systems. For more technical details, see the Qt Bug Report QTBUG-81272.

Detection Methods for CVE-2020-0570

Indicators of Compromise

• Unexpected library files appearing in directories within the Qt application's search path
• Qt-based applications loading libraries from unusual or user-writable directories
• Process execution logs showing Qt applications loading unsigned or unverified libraries
• Suspicious file creation events in directories commonly targeted for search path attacks

Detection Strategies

• Monitor file system events for library creation in user-writable directories that precede system library paths
• Implement application whitelisting to detect loading of unauthorized libraries by Qt-based applications
• Deploy endpoint detection and response (EDR) solutions to identify anomalous library loading behavior
• Audit running processes for Qt applications loading libraries from non-standard locations

Monitoring Recommendations

• Enable detailed logging for library loading events on systems running Qt-based applications
• Configure SIEM rules to alert on unexpected library loads in Qt application execution contexts
• Regularly audit the search path configuration for Qt-based applications in your environment
• Monitor for modifications to environment variables that affect library search paths

How to Mitigate CVE-2020-0570

Immediate Actions Required

• Upgrade Qt Library to version 5.14.0, 5.12.7, or 5.9.10 or later depending on your version branch
• Review and audit all Qt-based applications deployed in your environment
• Restrict write access to directories in the library search path for non-privileged users
• Apply vendor patches from Red Hat for Enterprise Linux 7.0 and 8.0 systems

Patch Information

Qt has released patched versions addressing this vulnerability. Organizations should upgrade to Qt 5.14.0 or later for the 5.14.x branch, 5.12.7 or later for the 5.12.x branch, or 5.9.10 or later for the 5.9.x branch. Red Hat has also released updates for Enterprise Linux systems as documented in their Bugzilla Report #1800604.

For detailed patch information and release notes, refer to the Qt Development Mailing List Post.

Workarounds

• Restrict write permissions on directories that appear in the library search path before system directories
• Set explicit and secure library paths for Qt applications using environment variables like LD_LIBRARY_PATH or QT_PLUGIN_PATH
• Run Qt-based applications with minimal required privileges to limit the impact of exploitation
• Implement application sandboxing to isolate Qt applications from sensitive system resources

# Example: Restricting library search path for Qt applications
export QT_PLUGIN_PATH=/usr/lib/qt/plugins
export LD_LIBRARY_PATH=/usr/lib/qt:/usr/lib

# Ensure user-writable directories are not in the search path
chmod 755 /usr/lib/qt
chmod 755 /usr/lib/qt/plugins