CVE-2018-7838 in M580 CPU BMEP582040
Summary
by MITRE
A CWE-119 Buffer Errors vulnerability exists in Modicon M580 CPU - BMEP582040, all versions before V2.90, and Modicon Ethernet Module BMENOC0301, all versions before V2.16, which could cause denial of service on the FTP service of the controller or the Ethernet BMENOC module when it receives a FTP CWD command with a data length greater than 1020 bytes. A power cycle is then needed to reactivate the FTP service.
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Analysis
by VulDB Data Team • 10/26/2023
The vulnerability identified as CVE-2018-7838 represents a critical buffer overflow condition classified under CWE-119, affecting industrial control systems manufactured by Schneider Electric. This flaw specifically impacts the Modicon M580 CPU with firmware version BMEP582040 prior to V2.90 and the Modicon Ethernet Module BMENOC0301 with firmware version BMENOC0301 prior to V2.16. The vulnerability manifests within the File Transfer Protocol implementation of these industrial controllers, creating a significant operational risk for critical infrastructure environments where continuous system availability is paramount.
The technical mechanism of this vulnerability involves an insufficient bounds check during processing of the FTP CWD (Change Working Directory) command. When an attacker sends a specially crafted FTP CWD command containing data exceeding 1020 bytes, the system fails to properly validate the input length before attempting to process it within a fixed-size buffer. This buffer overflow condition results in memory corruption that crashes the FTP service thread, effectively rendering the FTP functionality unavailable. The flaw demonstrates characteristics consistent with stack-based buffer overflow attacks where excessive input data overwrites adjacent memory locations, potentially causing unpredictable behavior and system instability.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects industrial control systems that require high availability and reliability. In industrial environments, the need for a power cycle to restore FTP service functionality creates additional operational challenges, particularly in scenarios where remote access to controllers is essential for maintenance, configuration updates, or troubleshooting. The vulnerability affects systems where FTP services are commonly used for firmware updates, configuration file transfers, and data logging operations, making it particularly dangerous in critical infrastructure sectors such as manufacturing, energy, and water treatment facilities where controller availability directly impacts production processes.
The exploitation of this vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under the execution and persistence domains, where adversaries may leverage service disruption as part of broader operational technology compromise strategies. Organizations should consider implementing network segmentation to isolate industrial control systems from general network access, limiting the potential attack surface for such vulnerabilities. The recommended mitigation approach includes immediate firmware updates to versions V2.90 and V2.16 respectively for the affected hardware components, along with implementing network-based controls such as firewall rules that restrict FTP access to authorized administrative networks only. Additionally, monitoring for unusual FTP activity patterns and implementing intrusion detection systems can help identify potential exploitation attempts before they result in service disruption. Organizations should also establish robust backup and recovery procedures for industrial control system configurations to minimize downtime during remediation activities and ensure operational continuity during the vulnerability resolution process.