A new Common Vulnerabilities and Exposures (CVE) entry, CVE-2022-1736, has been registered to address a security flaw found in Ubuntu's default configuration of the gnome-control-center. This flaw allows potential attackers to gain unauthorized access to a user's computer by exploiting the Remote Desktop Sharing feature enabled by default. This article will delve into the details of this vulnerability, its potential exploits, and how it can be fixed and mitigated.
Vulnerability Details
The core issue lies in Ubuntu's gnome-control-center, which is a unified control panel for managing essential system settings and preferences. The configuration file for the gnome-control-center determines whether certain features are enabled by default, including Remote Desktop Sharing.
Remote Desktop Sharing allows users to view and control a desktop environment remotely over a network connection. However, it can also be exploited by attackers if not properly secured. In this specific case, the default configuration file erroneously enables Remote Desktop Sharing without requiring user consent or authentication, thereby providing an open door for potential intruders.
The code snippet below shows an excerpt from the default configuration file found in '/usr/share/glib-2./schemas/org.gnome.Vino.gschema.xml':
<schemalist>
<schema id="org.gnome.Vino" path="/org/gnome/desktop/remote-access/">
<key name="enabled" type="b">
<default>true</default>
<summary>Enable remote access to the desktop</summary>
<description>Whether to allow remote access to the desktop</description>
</key>
...
</schema>
</schemalist>
The 'enabled' key, set to 'true' by default, causes Remote Desktop Sharing to be active upon installation.
Exploit Details
An attacker can exploit this vulnerability by scanning for open VNC (Virtual Network Computing) ports on a target system running a vulnerable version of Ubuntu with the affected configuration. Once an open port is discovered, the attacker can use various VNC clients to gain unauthorized access to the system's desktop environment, potentially leading to unauthorized usage, data theft, and malware installation.
The proof-of-concept exploit below demonstrates how an attacker might scan a target IP range for open VNC ports using the popular network scanning tool, Nmap:
$ nmap -p 590-5905 --open <target-ip-range>
Original References
The vulnerability is documented in the official CVE database under the unique identifier CVE-2022-1736:
- CVE-2022-1736
- National Vulnerability Database
Mitigation and Fix
To mitigate this vulnerability, users are advised to disable Remote Desktop Sharing if it is not required or to configure it securely with proper authentication methods. The necessary steps are as follows:
Set the 'Screen Sharing' setting to 'Off'.
Alternatively, you can modify the gnome-control-center configuration file to disable Remote Desktop Sharing by default:
Open a terminal and use a text editor to edit the configuration file
$ sudo nano /usr/share/glib-2./schemas/org.gnome.Vino.gschema.xml
Change the 'enabled' key's default value from 'true' to 'false'
<key name="enabled" type="b">
<default>false</default>
<summary>Enable remote access to the desktop</summary>
<description>Whether to allow remote access to the desktop</description>
</key>
Recompile the schema
$ sudo glib-compile-schemas /usr/share/glib-2./schemas
Conclusion
CVE-2022-1736 highlights the importance of thoroughly auditing default configurations for security vulnerabilities. By understanding the nature of this vulnerability and taking the necessary steps to secure their systems, users can effectively mitigate the risk of unauthorized access and potential exploits. It is crucial to stay informed about emerging threats and to apply necessary security updates to protect your digital assets.
Timeline
Published on: 01/31/2025 02:15:28 UTC
Last modified on: 02/07/2025 16:15:33 UTC