OpAMP client reads unbounded HTTP response bodies

Summary

When receiving responses from the OpAMP server over HTTP, the OpAMP client allocates an unbounded buffer to read all bytes from the server, with no upper-bound on the number of bytes consumed.

This could cause memory exhaustion in the consuming application if the configured OpAMP server is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned in the response.

Details

#2926 introduced the initial HTTP transport components which uses ReadAsByteArrayAsync to copy the HttpResponseMessage.Content into a byte array. This code path allows an unbounded read of the entire HTTP response message.

Impact

If an application using the OpAMP client is configured to use an OpAMP server that is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned in the response, the application could have its memory exhausted and create a denial-of-service condition.

Mitigation

The application's configured OpAMP server needs to behave maliciously. If the OpAMP server is a well-behaved implementation, response bodies should not be excessively large.

Workarounds

None known.

Remediation

#4116 updates the OpAMP client HTTP transport to limit the maximum size of responses to 128KB.

Resources

• #2926
• #4116
• CWE-789