CVE-2019-5182 in PFC200
Summary
by MITRE
An exploitable stack buffer overflow vulnerability vulnerability exists in the iocheckd service ‘I/O-Check’ functionality of WAGO PFC 200 Firmware version 03.02.02(14). An attacker can send a specially crafted packet to trigger the parsing of this cache file.The destination buffer sp+0x440 is overflowed with the call to sprintf() for any type values that are greater than 1024-len(‘/etc/config-tools/config_interfaces interface=X1 state=enabled config-type=‘) in length. A type value of length 0x3d9 will cause the service to crash.
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Analysis
by VulDB Data Team • 04/13/2024
The vulnerability CVE-2019-5182 represents a critical stack buffer overflow in the iocheckd service of WAGO PFC 200 industrial control devices running firmware version 03.02.02(14). This issue resides within the I/O-Check functionality, which is designed to monitor and manage input/output operations in industrial automation environments. The flaw stems from improper input validation during packet processing, specifically when handling cache file parsing operations that occur within the service's memory management routines. The vulnerability manifests when the system processes specially crafted network packets that contain malformed type values, creating a condition where attacker-controlled data exceeds the allocated buffer space.
The technical implementation of this vulnerability involves a direct stack-based buffer overflow occurring at the memory location sp+0x440, where the sprintf() function is invoked to process user-supplied data. The buffer has a fixed size limitation that cannot accommodate type values exceeding 1024 minus the length of the configuration string "/etc/config-tools/config_interfaces interface=X1 state=enabled config-type=". This specific constraint creates a predictable overflow window where any input exceeding 0x3d9 (985 decimal) characters in length will trigger the buffer overflow condition. The vulnerability demonstrates characteristics consistent with CWE-121 Stack-based Buffer Overflow, where insufficient bounds checking allows arbitrary data to overwrite adjacent stack memory locations, potentially including return addresses and function pointers.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides a potential pathway for remote code execution within industrial control environments. The iocheckd service operates with elevated privileges typically required for system-level operations, making successful exploitation particularly dangerous in industrial settings where these devices control critical infrastructure. Attackers could leverage this vulnerability to gain unauthorized access to the device, potentially leading to manipulation of industrial processes, data corruption, or complete system compromise. The vulnerability's exploitability is enhanced by the fact that it requires minimal network access and can be triggered through standard network communication protocols, making it attractive to threat actors targeting industrial control systems.
Security mitigation strategies should prioritize immediate firmware updates from WAGO to address the identified buffer overflow condition. Network segmentation and access controls should be implemented to limit exposure of these industrial devices to untrusted networks, following ATT&CK technique T1046 Network Service Scanning and T1071 Application Layer Protocol. Additional protective measures include implementing intrusion detection systems to monitor for anomalous packet patterns that might indicate exploitation attempts, and conducting regular security assessments of industrial control network configurations. The vulnerability underscores the importance of robust input validation and memory safety practices in embedded systems, particularly those operating in critical infrastructure environments where security failures can have severe operational consequences. Organizations should also consider implementing network monitoring solutions specifically designed for industrial control systems to detect and prevent exploitation attempts targeting similar vulnerabilities in operational technology environments.