CVE-2019-5170 in PFC200
Summary
by MITRE
An exploitable command injection vulnerability exists in the iocheckd service ‘I/O-Check’ function of the WAGO PFC 200 Firmware version 03.02.02(14). A specially crafted XML cache file written to a specific location on the device can be used to inject OS commands. An attacker can send a specially crafted packet to trigger the parsing of this cache file.At 0x1e87c the extracted hostname value from the xml file is used as an argument to /etc/config-tools/change_hostname hostname=<contents of hostname node> using sprintf(). This command is later executed via a call to system().
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Analysis
by VulDB Data Team • 04/13/2024
The vulnerability identified as CVE-2019-5170 represents a critical command injection flaw within the iocheckd service of WAGO PFC 200 industrial control devices running firmware version 03.02.02(14). This issue stems from improper input validation and sanitization within the I/O-Check functionality, creating a pathway for remote attackers to execute arbitrary operating system commands on affected devices. The vulnerability manifests through a specific code execution point at address 0x1e87c where the system extracts hostname values from XML cache files and directly incorporates them into system commands without adequate sanitization or validation. The affected service processes XML files stored in a specific location on the device, making it accessible to attackers who can manipulate these files to inject malicious commands. This command injection vulnerability falls under CWE-77 which specifically addresses command injection flaws, where user-supplied data is improperly incorporated into operating system commands, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The exploitation process begins with an attacker crafting a malicious XML cache file containing specially formatted hostname data that, when processed by the vulnerable iocheckd service, gets passed directly to the system command through sprintf() formatting. The vulnerability's impact extends beyond simple command execution as it allows attackers to potentially gain full control over the industrial control device, enabling them to modify system configurations, install persistent backdoors, or disrupt critical industrial processes. The attack vector is particularly concerning as it requires minimal privileges to exploit, relying only on the ability to write files to a specific location on the device and send packets to trigger the parsing mechanism. This makes the vulnerability highly attractive to threat actors targeting industrial control systems, as it provides a straightforward path to device compromise. The security implications are severe for operational technology environments where WAGO PFC 200 devices are deployed, as these industrial controllers often form the backbone of critical infrastructure operations. The vulnerability's persistence stems from the lack of input validation at the point where the hostname value is extracted from XML and incorporated into the system command execution flow, creating a direct chain of trust that allows arbitrary code execution. Organizations utilizing these devices face significant risk of unauthorized access and potential operational disruption, particularly in environments where industrial control systems are not adequately segmented from corporate networks. The vulnerability's exploitation does not require specialized knowledge beyond basic understanding of XML file manipulation and command injection techniques, making it accessible to a broad range of threat actors. Remediation efforts should focus on implementing proper input validation and sanitization for all user-supplied data, particularly in XML parsing contexts where data is extracted and used in system commands. Additionally, network segmentation and access controls should be implemented to restrict unauthorized file system access and network communication to affected services. The vulnerability highlights the importance of secure coding practices in industrial control systems and the critical need for proper input validation in all data processing functions. Security patches should address the root cause by ensuring that any data extracted from XML files is properly sanitized before being used in system command execution contexts. The broader implications for industrial cybersecurity underscore the necessity of regular vulnerability assessments and firmware updates for critical infrastructure components. Organizations should implement monitoring solutions to detect suspicious file modifications and network traffic patterns that may indicate exploitation attempts. This vulnerability serves as a reminder of the critical security considerations required for industrial control systems, where the stakes of exploitation extend beyond traditional information technology concerns to potentially impact physical operations and safety systems. The affected WAGO PFC 200 devices represent a significant risk to industrial environments, particularly those where operational technology and information technology systems are not properly isolated. The vulnerability's impact on industrial control systems emphasizes the need for comprehensive security frameworks that address both traditional IT security concerns and the unique challenges of operational technology environments. Proper security posture requires not only patch management but also architectural considerations such as network segmentation, access controls, and continuous monitoring to protect against similar vulnerabilities in industrial control system components.