CVE-2018-4300 in CUPS
Summary
by MITRE
The session cookie generated by the CUPS web interface was easy to guess on Linux, allowing unauthorized scripted access to the web interface when the web interface is enabled. This issue affected versions prior to v2.2.10.
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Analysis
by VulDB Data Team • 08/21/2023
The vulnerability identified as CVE-2018-4300 represents a critical weakness in the Common Unix Printing System (CUPS) web interface implementation on Linux systems. This flaw specifically targets the session management mechanism that governs user authentication and access control within the printing system's web administration interface. The issue stems from insufficient entropy in the session cookie generation algorithm, creating predictable authentication tokens that adversaries can easily reproduce without legitimate credentials. Such weaknesses in session management directly violate fundamental security principles and create pathways for unauthorized access to privileged system functionalities.
The technical root cause of this vulnerability lies in the cryptographic weakness of the session cookie generation process within CUPS versions prior to 2.2.10. When the web interface is enabled, the system creates session identifiers that lack adequate randomness and unpredictability characteristics. This weakness maps directly to CWE-330, which addresses the use of insufficiently random values in security-sensitive contexts. The predictable nature of these session identifiers allows attackers to craft valid session tokens through automated scripts or brute force techniques, effectively bypassing the authentication mechanism entirely. The vulnerability demonstrates a failure in implementing proper cryptographically secure random number generation for session management components.
The operational impact of CVE-2018-4300 extends beyond simple unauthorized access to the CUPS web interface. An attacker who successfully exploits this vulnerability gains the ability to perform administrative operations on the printing system, including adding or removing printers, modifying print queue configurations, changing user permissions, and potentially accessing sensitive system information. This unauthorized access can lead to disruption of printing services, data exfiltration through print jobs, or even lateral movement within the network if the compromised system serves as a gateway to other resources. The vulnerability affects organizations that rely on CUPS for print management, particularly those with web interfaces enabled, creating risk for both enterprise and small business environments.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to CUPS version 2.2.10 or later, which contains the patched session cookie generation algorithm. System administrators should also consider disabling the web interface entirely if it is not required for operations, as this eliminates the attack surface entirely. Additional protective measures include implementing network segmentation to isolate printing systems, monitoring for suspicious authentication patterns, and ensuring that only authorized personnel have access to systems running the vulnerable CUPS web interface. The mitigation strategy should align with ATT&CK technique T1078 which addresses valid accounts and privilege escalation through unauthorized access to administrative interfaces. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar weaknesses in other system components that rely on predictable session management mechanisms.