When Suricata handles files over SMB, it does not wait for the
NBSS record to be complete, and can stream the payload to the
file... But it did not check the consistency of the SMB record
length being read or written against the NBSS record length.
This could lead to an evasion where an attacker crafts a SMB
write with a too big Length field, and then sends its evil
payload, even if the server returned an error for the write request.
Ticket: #5770
Evasion scenario is
- a first dummy write of one byte at offset 0 is done
- the second full write of EICAR at offset 0 is then done
and does not trigger detection
The last write had the final value, and as we cannot "cancel"
the previous write, we set an event which is then transformed into
an app-layer decoder alert
Implement SMB app-layer parser for SMB1/2/3. Features:
- file extraction
- eve logging
- existing dce keyword support
- smb_share/smb_named_pipe keyword support (stickybuffers)
- auth meta data extraction (ntlmssp, kerberos5)