Detections
Analytics
CVE-2019-18792
critical
Description
An issue was discovered in Suricata 5.0.0. It is possible to bypass/evade any tcp based signature by overlapping a TCP segment with a fake FIN packet. The fake FIN packet is injected just before the PUSH ACK packet we want to bypass. The PUSH ACK packet (containing the data) will be ignored by Suricata because it overlaps the FIN packet (the sequence and ack number are identical in the two packets). The client will ignore the fake FIN packet because the ACK flag is not set. Both linux and windows clients are ignoring the injected packet.
References
https://redmine.openinfosecfoundation.org/issues/3394
https://redmine.openinfosecfoundation.org/issues/3324
https://lists.debian.org/debian-lts-announce/2020/01/msg00032.html
https://github.com/OISF/suricata/commit/fa692df37a796c3330c81988d15ef1a219afc006
https://github.com/OISF/suricata/commit/1c63d3905852f746ccde7e2585600b2199cefb4b