Description

In October 2023, a critical advisory was issued for CVE-2023-43208, a pre-authenticated remote code execution vulnerability impacting NextGen Mirth Connect, a widely used open source data integration platform in healthcare organizations. The vulnerability stemmed from insecure usage of the Java XStream library for unmarshalling XML payloads. CVE-2023-43208 originated from an incomplete patch for CVE-2023-37679, another pre-auth RCE vulnerability. Despite being reportedly patched in Mirth Connect 4.4.0, investigations revealed that the patch was inadequate, leading to the discovery of CVE-2023-43208. Tracing the code revealed vulnerabilities in Mirth servlets, where authentication checks were bypassed prior to XML payload unmarshalling, enabling exploitation. Subsequent testing across different Mirth versions and Java environments highlighted variations in exploit success rates. To create a general exploit for CVE-2023-37679, modifications were made to payloads to bypass limitations encountered in older Mirth versions and newer Java environments. Additionally, an alternative to the patched ProcessBuilder class was identified to execute system commands, demonstrating the persistence of vulnerabilities despite attempted fixes. Mirth Connect 4.4.1 addressed CVE-2023-43208 by eliminating the XStream denylist and implementing an explicit allowlist of safe classes. Detection of vulnerable instances can be done by checking the server version, with any version below 4.4.1 being potentially exploitable. Exploitation of this vulnerability poses significant risks, particularly in healthcare settings, where sensitive data may be compromised. Overall, CVE-2023-43208/CVE-2023-37679 represents a serious threat, underscoring the importance of timely patching and robust security measures in healthcare IT infrastructure.