CVE-2019-8842 in macOS
Summary
by MITRE • 10/28/2020
A buffer overflow was addressed with improved bounds checking. This issue is fixed in macOS Catalina 10.15.2, Security Update 2019-002 Mojave, and Security Update 2019-007 High Sierra. In certain configurations, a remote attacker may be able to submit arbitrary print jobs.
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Analysis
by VulDB Data Team • 11/29/2020
The vulnerability identified as CVE-2019-8842 represents a critical buffer overflow flaw within Apple's printing subsystem that affects multiple versions of macOS. This issue resides in the way the system handles print job submissions, creating a scenario where malicious actors can exploit improper bounds checking mechanisms to execute arbitrary code. The vulnerability is particularly concerning because it allows remote attackers to submit crafted print jobs that trigger the buffer overflow condition, potentially leading to unauthorized system access and execution of malicious payloads. The affected configurations typically involve networked printing environments where the print server component is accessible over the network, making it a significant threat vector for attackers seeking to compromise macOS systems through print services.
Technical exploitation of this vulnerability occurs when a remote attacker crafts a specially formatted print job that exceeds the allocated buffer space within the printing subsystem. The insufficient bounds checking allows the malicious data to overwrite adjacent memory locations, potentially corrupting critical system structures or injecting executable code. This type of buffer overflow vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how improper input validation can lead to arbitrary code execution. The flaw specifically impacts the print queue processing mechanism within the macOS kernel, where print job data is handled before being forwarded to the actual printing hardware. Attackers can leverage this vulnerability to execute code with the privileges of the print daemon process, which typically runs with elevated permissions, potentially allowing for privilege escalation attacks.
The operational impact of CVE-2019-8842 extends beyond simple remote code execution, as it can enable attackers to establish persistent access to affected systems while potentially remaining undetected within network environments. Organizations with networked printing infrastructure face the highest risk, particularly those that do not properly isolate print servers or implement adequate network segmentation. The vulnerability affects not only the end-user systems but also print servers and networked printers that may be running older versions of macOS or that have not received the necessary security updates. This creates a multi-layered attack surface where attackers can compromise systems through various entry points, including direct printer connections, network print server access, or through compromised user devices that attempt to submit print jobs to vulnerable systems. The security implications are further compounded by the fact that print jobs are often processed automatically without user interaction, making it easier for attackers to exploit this vulnerability without detection.
Mitigation strategies for CVE-2019-8842 require immediate implementation of the vendor-provided security updates, which include macOS Catalina 10.15.2, Security Update 2019-002 for Mojave, and Security Update 2019-007 for High Sierra. System administrators should prioritize patching affected systems and ensure that all networked print services are updated to prevent exploitation. Additional protective measures include implementing network segmentation to isolate print servers from critical network segments, disabling unnecessary print services, and monitoring print job submissions for anomalous patterns that might indicate exploitation attempts. Organizations should also consider implementing network access controls and firewall rules to restrict access to print services, particularly those running on macOS systems. The ATT&CK framework categorizes this vulnerability under privilege escalation and execution techniques, emphasizing the need for comprehensive monitoring of system processes and print job handling activities. Regular security assessments of print infrastructure and implementation of principle of least privilege for print service accounts can significantly reduce the attack surface and prevent successful exploitation of this vulnerability.