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AUSCERT External Security Bulletin Redistribution
suricata security update
31 January 2020
AusCERT Security Bulletin Summary
Operating System: Debian GNU/Linux 8
UNIX variants (UNIX, Linux, OSX)
Impact/Access: Provide Misleading Information -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
CVE Names: CVE-2019-18792 CVE-2019-18625
Comment: This advisory references vulnerabilities in products which run on
platforms other than Debian. It is recommended that administrators
running suricata check for an updated version of the software for
their operating system.
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Package : suricata
Version : 2.0.7-2+deb8u5
CVE ID : CVE-2019-18625 CVE-2019-18792
Two vulnerabilities have recently been discovered in the stream-tcp code
of the intrusion detection and prevention tool Suricata.
It was possible to bypass/evade any tcp based signature by faking a
closed TCP session using an evil server. After the TCP SYN packet, it
was possible to inject a RST ACK and a FIN ACK packet with a bad TCP
Timestamp option. The client would have ignored the RST ACK and the
FIN ACK packets because of the bad TCP Timestamp option.
It was possible to bypass/evade any tcp based signature by
overlapping a TCP segment with a fake FIN packet. The fake FIN packet
had to be injected just before the PUSH ACK packet we wanted to
bypass. The PUSH ACK packet (containing the data) would have been
ignored by Suricata because it would have overlapped the FIN packet
(the sequence and ack number are identical in the two packets). The
client would have ignored the fake FIN packet because the ACK flag
would not have been set.
For Debian 8 "Jessie", these problems have been fixed in version
We recommend that you upgrade your suricata packages.
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
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