CVE-2018-20768 in WorkCentre
Summary
by MITRE
An issue was discovered on Xerox WorkCentre 3655, 3655i, 58XX, 58XXi, 59XX, 59XXi, 6655, 6655i, 72XX, 72XXi, 78XX, 78XXi, 7970, 7970i, EC7836, and EC7856 devices before R18-05 073.xxx.0487.15000. An attacker can execute PHP code by leveraging a writable file.
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Analysis
by VulDB Data Team • 05/29/2020
This vulnerability exists within multiple Xerox WorkCentre multifunction devices running firmware versions prior to R18-05 073.xxx.0487.15000 and affects models including 3655, 58XX, 59XX, 6655, 72XX, 78XX, 7970, EC7836, and EC7856 series. The flaw represents a critical security weakness that allows remote code execution through PHP code injection, enabling attackers to gain unauthorized access to the device's underlying system. This vulnerability falls under the category of insecure direct object reference and improper input validation as classified by CWE-22 and CWE-20 respectively, with implications for privilege escalation and system compromise.
The technical exploitation occurs through a writable file vulnerability that permits an attacker to upload and execute PHP scripts on the device. This write access point enables the execution of malicious code with the privileges of the web server process, potentially allowing full system compromise. The vulnerability stems from inadequate file permission controls and insufficient input sanitization mechanisms within the device's web interface, creating an attack surface that aligns with ATT&CK technique T1059.007 for command and scripting interpreter. The affected devices operate with web-based management interfaces that fail to properly validate file uploads, creating a path for attackers to place malicious PHP payloads in writable directories.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it provides attackers with persistent control over the affected devices. Once exploited, attackers can execute arbitrary commands, potentially leading to data exfiltration, network reconnaissance, or use of the compromised device as a pivot point for further attacks within the network. The vulnerability affects devices that are commonly found in enterprise environments where print servers and multifunction devices serve as critical infrastructure components. The risk is particularly elevated in environments where these devices are not properly segmented or monitored, as they may provide attackers with access to sensitive corporate information through the print queue or document management systems.
Organizations should immediately apply the firmware update released by Xerox to address this vulnerability, specifically targeting the R18-05 073.xxx.0487.15000 version or later. Network segmentation should be implemented to isolate these devices from critical network segments, and access controls should be enforced through proper authentication mechanisms. Regular vulnerability assessments should include scanning for exposed print servers and multifunction devices, with monitoring for unusual file upload activities or command execution patterns. The mitigation strategy should also include implementing network intrusion detection systems to identify potential exploitation attempts and establishing incident response procedures specifically for device compromise scenarios. Additionally, organizations should consider disabling unnecessary web services on these devices and implementing strict firewall rules to limit access to only authorized administrative users. This vulnerability demonstrates the importance of maintaining current firmware versions and proper security configuration management for networked devices, as it represents a classic example of how outdated software can create persistent security risks in enterprise environments.