CVE-2017-18248 in CUPS
Summary
by MITRE
The add_job function in scheduler/ipp.c in CUPS before 2.2.6, when D-Bus support is enabled, can be crashed by remote attackers by sending print jobs with an invalid username, related to a D-Bus notification.
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Analysis
by VulDB Data Team • 02/24/2023
The vulnerability identified as CVE-2017-18248 represents a critical buffer overflow condition within the Common Unix Printing System CUPS software version 2.2.5 and earlier. This flaw exists specifically in the scheduler/ipp.c component when D-Bus support is enabled, creating a remote code execution vector that allows attackers to crash the printing service through malformed print job submissions. The issue stems from inadequate input validation within the add_job function, which fails to properly handle invalid username parameters during the D-Bus notification process. This vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and demonstrates how improper handling of user-supplied data can lead to service disruption and potential system compromise.
The technical exploitation of this vulnerability occurs when remote attackers send print jobs containing malformed username data to a CUPS server with D-Bus support enabled. The add_job function processes these requests without sufficient validation of the username parameter, leading to memory corruption when the system attempts to handle the invalid input during D-Bus notification generation. This results in a crash of the CUPS scheduler process, effectively causing a denial of service condition that prevents legitimate print jobs from being processed. The vulnerability is particularly concerning because it can be triggered remotely without authentication, making it an attractive target for attackers seeking to disrupt printing services in enterprise environments.
The operational impact of CVE-2017-18248 extends beyond simple service disruption to potentially compromise entire printing infrastructures within organizations. In enterprise environments where CUPS serves as the primary printing system, this vulnerability can lead to significant operational downtime affecting productivity across multiple departments. The remote nature of the attack means that adversaries can exploit this weakness from anywhere on the network, making traditional network segmentation ineffective as a mitigation strategy. Organizations relying on CUPS for print management may experience cascading effects as print queues become unavailable, potentially disrupting critical business processes that depend on document printing and distribution.
Security practitioners should implement immediate mitigations including upgrading to CUPS version 2.2.6 or later, which contains patches addressing this specific vulnerability. Additionally, organizations should disable D-Bus support in CUPS configuration when it is not required for printing operations, reducing the attack surface. Network segmentation strategies should be reinforced to limit access to printing services, and monitoring should be implemented to detect unusual print job patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.001, which covers network disruption, and represents a classic example of how improper input validation can lead to system instability. Organizations should also consider implementing intrusion detection systems that can identify malformed print job requests and automated response mechanisms that can quarantine suspicious traffic to prevent exploitation of this and similar vulnerabilities.