ExploitCVE-2024-47176
Binding to an Unrestricted IP Address (CWE-1327)
Summary
A critical vulnerability has been discovered in OpenPrinting CUPS, specifically in the cups-browsed component. This component, responsible for discovering printers on a network and adding them to the system, binds to all interfaces on UDP port 631 and accepts custom packets from any untrusted source. The vulnerability can be exploited from outside the local area network if the computer is exposed to the public internet. When a printer is discovered, either through a UDP packet or mDNS, its IPP or IPPS URL is automatically contacted by cups-browsed, and a Get-Printer-Attributes request is sent. This can potentially leak sensitive system information to an attacker via the User-Agent header.
Impact
The impact of this vulnerability is severe. An attacker can potentially execute arbitrary commands on the target system remotely without authentication. This could lead to complete system compromise, including: 1. Unauthorized access to sensitive data 2. Installation of malware or backdoors 3. Use of the compromised system as a launching point for further attacks 4. Disruption of printing services and other system operations The vulnerability is particularly concerning because it can be exploited from the public internet, potentially exposing a large number of systems to remote attacks if their CUPS services are enabled and exposed. The CVSS v3 base score for this vulnerability is 8.3, indicating a high severity level with a network attack vector, high attack complexity, and no required privileges but required user interaction.
Exploitation
One proof-of-concept exploit is available on github.com. Its exploitation has been reported by various sources, including reddit.com.
Patch
A patch has been added on 2024-09-27, as indicated by the patchDetails in the vulnerability data. The security team should check the provided URL (https://bugzilla.redhat.com/show_bug.cgi?id=2314252) for the latest information on the patch and its availability for their specific systems.
Mitigation
While waiting for an official patch to be fully implemented, the following mitigation steps are recommended: 1. Disable or limit access to the cups-browsed service if it's not critically needed. 2. If the service must remain active, use firewall rules to restrict access to port 631 only from trusted networks or hosts. 3. Implement network segmentation to isolate printing services from critical systems and the public internet. 4. Regularly monitor system logs for any suspicious activities related to CUPS or printing services. 5. Keep the CUPS software and all related components up to date with the latest stable versions. 6. Consider using application whitelisting to prevent unauthorized command execution. 7. Implement strong authentication mechanisms for accessing printing services, even though this vulnerability bypasses authentication. Given the high severity of this vulnerability (CVSS score 8.3) and its potential for remote exploitation without authentication, patching should be prioritized as soon as an official patch becomes available. In the meantime, implement the above mitigation strategies to reduce the risk of exploitation.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Timeline
Detection for the vulnerability has been added to Qualys (380563)
Feedly found the first article mentioning CVE-2024-47176. See article
CVE-2024-47176 is a critical vulnerability in cups-browsed (up to version 2.0.1) that allows attackers to exploit improperly validated URLs received during printer discovery, potentially leading to arbitrary URL requests. A proof-of-concept exploit is available, and while there is no patch currently, mitigations include disabling cups-browserd and stopping UDP traffic on port 631. The vulnerability poses risks primarily to systems using CUPS for printing, particularly if they are exposed to local network attacks. See article
Feedly estimated the CVSS score as HIGH
Attacks in the wild have been reported by Managed Service Providers. See article
NVD published the first details for CVE-2024-47176
A CVSS base score of 8.3 has been assigned.
Detection for the vulnerability has been added to Qualys (244433)