CVE-2017-6398 in InterScan Messaging Security
Summary
by MITRE
An issue was discovered in Trend Micro InterScan Messaging Security (Virtual Appliance) 9.1-1600. An authenticated user can execute a terminal command in the context of the web server user (which is root). Besides, the default installation of IMSVA comes with default administrator credentials. The saveCert.imss endpoint takes several user inputs and performs blacklisting. After that, it uses them as arguments to a predefined operating-system command without proper sanitization. However, because of an improper blacklisting rule, it's possible to inject arbitrary commands into it.
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Analysis
by VulDB Data Team • 09/06/2020
The vulnerability identified as CVE-2017-6398 resides within Trend Micro InterScan Messaging Security Virtual Appliance version 9.1-1600, representing a critical command injection flaw that fundamentally compromises the security posture of the messaging security platform. This issue manifests through the saveCert.imss endpoint which processes user inputs intended for certificate management operations, creating a dangerous attack surface where legitimate administrative functionality becomes a vector for privilege escalation. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before incorporating it into operating system commands, effectively allowing authenticated attackers to execute arbitrary code with the highest possible privileges available to the web server process.
The technical implementation of this vulnerability follows a classic command injection pattern where user-controllable parameters are directly concatenated into system commands without proper sanitization or encoding. The saveCert.imss endpoint employs a blacklisting approach to prevent malicious input, but this method proves fundamentally flawed due to incomplete or improperly configured filtering rules that fail to account for all possible command injection techniques. Attackers can bypass these restrictions by crafting input sequences that circumvent the blacklisting mechanism, thereby enabling the execution of arbitrary terminal commands as the web server user who operates with root privileges. This design flaw directly violates security principle of least privilege and demonstrates a critical failure in input validation that aligns with CWE-77 and CWE-89 categories related to command injection vulnerabilities.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with complete system compromise capabilities through the web server user context. Since the web server runs with root privileges, successful exploitation grants full administrative control over the entire messaging security appliance, potentially enabling attackers to modify system configurations, extract sensitive data, install backdoors, or establish persistent access. The default administrator credentials present in the default installation configuration compound the risk significantly, as they eliminate the need for credential brute-forcing or social engineering attacks that would otherwise be required to achieve initial access. This combination of default credentials and command injection vulnerability creates a particularly dangerous scenario where minimal effort can result in complete system takeover, making it a prime target for automated exploitation campaigns.
Security professionals should recognize this vulnerability as a prime example of why blacklisting approaches to input validation are insufficient for preventing command injection attacks, as demonstrated by the ATT&CK framework's T1059.001 technique for command and scripting interpreter. Organizations should immediately implement mitigations including disabling unnecessary administrative functions, implementing proper input sanitization with whitelisting approaches, and enforcing strong authentication mechanisms. The vulnerability also highlights the importance of secure coding practices and proper privilege separation, as the web server should never operate with root privileges. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar issues in other components, as this vulnerability pattern frequently appears in web applications and network security appliances that fail to properly validate user inputs before executing system commands, making it a critical concern for organizations relying on messaging security solutions.