CVE-2020-9484: High severity IBM Data Risk Manager vulnerability

A deserialization flaw was discovered in Apache Tomcat's use of a FileStore. Under specific circumstances, an attacker can use a specially crafted request to trigger Remote Code Execution through deserialization of the file under their control. The highest threat from the vulnerability is to data confidentiality and integrity as well as system availability.

Apache Tomcat could allow a remote authenticated attacker to execute arbitrary code on the system, caused by an unsafe deserialization when the server is configured to use the PersistenceManager with a FileStore. By sending specially-crafted input, an attacker could exploit this vulnerability to execute arbitrary code on the system.

— IBM

When using Apache Tomcat versions 10.0.0-M1 to 10.0.0-M4, 9.0.0.M1 to 9.0.34, 8.5.0 to 8.5.54 and 7.0.0 to 7.0.103 if a) an attacker is able to control the contents and name of a file on the server; and b) the server is configured to use the PersistenceManager with a FileStore; and c) the PersistenceManager is configured with sessionAttributeValueClassNameFilter="null" (the default unless a SecurityManager is used) or a sufficiently lax filter to allow the attacker provided object to be deserialized; and d) the attacker knows the relative file path from the storage location used by FileStore to the file the attacker has control over; then, using a specifically crafted request, the attacker will be able to trigger remote code execution via deserialization of the file under their control. Note that all of conditions a) to d) must be true for the attack to succeed.