[LOG4J2-1226] Message instances are simply serialized. They mustn't.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.5
• Fix Version/s: 2.8
• Component/s: API
• Assignee: Remko Popma
• Reporter: Joern Huxhorn
• Created: 21/Dec/15 10:40
• Updated: 01/Jun/17 02:40
• Resolved: 05/Nov/16 15:26

Description

Right now, any Message instance used to call any log method are simply sent as they are.

Instead, the Throwable must be transformed into a ThrowableProxy. Custom Message implementations must be transformed into one of log4j's standard message implementations and care must be taken to convert the Parameters Object[] into String[] before the message is serialized.

Otherwise, deserialization will fail if a custom Throwable, custom Message or custom parameter is not contained in the classpath of the application receiving the serialized LogEvent.

I found those issues while implementing the circumvention for Apache Commons statement to widespread Java object de-serialisation vulnerability in Lilith.

Issue Links

• breaks: LOG4J2-1926 Remove dependency on RMI and Management APIs from log4j-api
• relates to: LOG4J2-1676 Some LogEvents may not carry a Throwable (Use Message.getThrowable() in log(Message) methods)
• relates to: LOG4J2-1465 Default layouts for various appenders could be more consistent
• relates to: LOG4J2-1663 Ensure SortedArrayStringMap can be serialized/deserialized regardless of content