A new open-source scanner has been released with a specific focus on detecting a critical vulnerability in the Common Unix Printing System (CUPS), known as CVE-2024-47176. This vulnerability, along with others in the chain, presents significant risks as it can potentially lead to remote code execution on UNIX and UNIX-like systems.
The primary objective of this scanner is to assist system administrators in identifying and mitigating these vulnerabilities before any malicious actors can exploit them. The potential impact of these vulnerabilities is substantial, as they could allow remote attackers to execute arbitrary code by adding or reconfiguring network printers.
CUPS, short for the Common Unix Printing System, is an open-source framework that is widely utilized for the management and control of printers on UNIX and UNIX-like systems. It enjoys support from UNIX, Linux, and some Apple devices, making it one of the most prevalent printing libraries available. Due to its widespread usage, any vulnerabilities discovered within CUPS can have far-reaching implications, affecting numerous systems globally.
Several critical vulnerabilities have been recently identified within CUPS, including CVE-2024-47176, CVE-2024-47076, CVE-2024-47175, and CVE-2024-47177. These vulnerabilities, when chained together, can enable a remote attacker to exploit network printers to execute arbitrary code when users attempt to print from them.
A detailed report by MalwareTech on Github highlights that the vulnerability CVE-2024-47176 resides in the cups-browsed daemon. The flaw arises from the fact that cups-browsed binds its control port (UDP port 631) to INADDR_ANY, making it accessible to the world without authentication. This accessibility means that anyone reaching the control port can instruct cups-browsed to perform printer discovery. Even if the port is not directly accessible from the internet due to firewalls or NAT configurations, it may still be reachable via local networks, opening up possibilities for privilege escalation and lateral movement within an organization’s network.
The scanning process for CVE-2024-47176 typically involves an attacker sending a specially crafted request to cups-browsed on UDP port 631, leading cups-browsed to reach a malicious URL controlled by the attacker. Attackers can identify vulnerable systems by triggering a vulnerable cups-browsed instance to issue an HTTP request to a server under their control.
To automate this scanning process, a newly released Python script called cups_scanner.py has been introduced. This script simplifies the setup of a temporary HTTP server and the scanning process itself. By launching the script, system administrators can automate the scanning process, capture callbacks from vulnerable instances, and analyze the results for potential vulnerabilities.
The script offers various command-line arguments for customization, including specifying the CIDR(s) to scan, setting up the local IP and port for hosting the HTTP server, and scanning all addresses, including network and broadcast addresses. This tool provides system administrators with an effective means of proactively identifying and addressing vulnerabilities in their CUPS configurations, thereby enhancing security across their networks.
In conclusion, the release of this open-source scanner represents a significant step towards enhancing the cybersecurity posture of UNIX and UNIX-like systems by enabling system administrators to detect and mitigate critical vulnerabilities in the Common Unix Printing System. By proactively addressing these issues, organizations can bolster their defenses against potential exploitation by malicious actors.