Critical Linux CUPS Vulnerabilities Allow Remote Code Execution

The article from The Hacker News discusses a set of critical security vulnerabilities in the Common Unix Printing System (CUPS) on Linux systems. These vulnerabilities, disclosed on September 26, 2024, could allow remote command execution under certain conditions. Here are the key points:

1. **Vulnerabilities Overview**:
– The vulnerabilities affect various CUPS components, including `cups-browsed`, `libcupsfilters`, and `libppd`.
– Specifically, CVE-2024-47176 and CVE-2024-47177 are highlighted, which involve improper handling of ‘New Printer Available’ announcements and poor validation of network data, respectively.

2. **Exploit Chain**:
– An attacker can exploit these vulnerabilities by sending a specially crafted packet to a vulnerable server, causing it to connect to a fake, attacker-controlled printer.
– The fake printer sends back a malicious configuration file, which executes arbitrary code when a print job is started from the victim’s computer.

3. **Affected Systems**:
– The vulnerabilities affect various Linux distributions, including Debian, Fedora, and Red Hat Enterprise Linux (RHEL).
– CUPS is commonly used on desktop computers and servers configured as print servers.

4. **Mitigation Steps**:
– To mitigate the risk, it is recommended to disable the `cups-browsed` service if it is not necessary.
– Blocking or restricting traffic to UDP port 631 can also help prevent exploitation.

5. **Patches and Response**:
– Patches for the vulnerabilities are currently being developed and are expected to be released soon.
– Organizations should apply recommended mitigation steps as soon as possible to reduce the risk of exploitation.

6. **Real-World Impact**:
– While the vulnerabilities are serious, the real-world impact is likely to be low because they require manual user interaction to complete the exploit chain.
– The attack chain involves tricking a user into printing from a malicious, attacker-controlled fake printer, which limits the potential for widespread exploitation.