CVE-2020-24054 in EXVF5C-2
Summary
by MITRE
The administration console of the Moog EXO Series EXVF5C-2 and EXVP7C2-3 units features a 'statusbroadcast' command that can spawn a given process repeatedly at a certain time interval as 'root'. One of the limitations of this feature is that it only takes a path to a binary without arguments; however, this can be circumvented using special shell variables, such as '${IFS}'. As a result, an attacker can execute arbitrary commands as 'root' on the units.
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Analysis
by VulDB Data Team • 08/22/2020
The vulnerability identified as CVE-2020-24054 resides within the administration console of Moog EXO Series EXVF5C-2 and EXVP7C2-3 units, representing a critical security flaw that enables unauthorized remote code execution with root privileges. This vulnerability specifically targets the 'statusbroadcast' command functionality which is designed to periodically execute processes at specified intervals. The flaw stems from inadequate input validation and sanitization within the command execution mechanism, creating a path for malicious actors to escalate their privileges and gain full system control. The affected devices operate within industrial control systems and monitoring environments where such vulnerabilities can have severe operational impacts.
The technical implementation of this vulnerability exploits a command injection weakness that occurs when the system processes the 'statusbroadcast' command without proper parameter validation. While the feature is intended to execute binaries at set intervals, it only accepts path specifications without supporting argument passing. Attackers can circumvent this limitation by leveraging shell variable expansion mechanisms, particularly the '${IFS}' variable which represents the Internal Field Separator in bash environments. This shell variable expansion technique allows attackers to inject additional commands and arguments into the execution context, effectively bypassing the intended restriction. The vulnerability manifests through the improper handling of user-supplied input in shell contexts, creating a classic command injection vector that can be exploited without authentication.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the affected industrial systems. Since the execution occurs with root privileges, adversaries can manipulate system configurations, access sensitive data, modify operational parameters, and potentially disrupt critical processes. The periodic nature of the command execution means that once exploited, the malicious commands will continue to run at predetermined intervals, providing persistent access and making detection more challenging. This vulnerability particularly affects industrial environments where these Moog units are deployed for monitoring and control purposes, potentially compromising the integrity of critical infrastructure operations. The lack of authentication requirements for exploitation makes this vulnerability especially dangerous in unsecured network environments.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected systems, as well as implementing network segmentation and access controls to limit exposure. Organizations should disable the problematic 'statusbroadcast' functionality when not actively required, and implement proper input validation and sanitization measures for all user-supplied parameters. Network monitoring should be enhanced to detect unusual command execution patterns and potential exploitation attempts. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and maps to ATT&CK technique T1059.004 for command and scripting interpreter. Additionally, this vulnerability demonstrates characteristics of privilege escalation through command injection, requiring comprehensive security assessments of industrial control system interfaces and proper security hardening practices for all administrative consoles in operational technology environments.