CVE-2018-5390 "SegmentSmack" - remote denial of service attack

This document (7023243) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15

Situation

"SegmentSmack" CVE-2018-5390 remote denial of service attack

Security researchers from FICORA have identified a remote denial of
service attack against the Linux kernel caused by inefficient
implementation of TCP segment reassembly, named "SegmentSmack".

A remote attacker could consume a lot of CPU resources in the kernel
networking stack with just a low bandwidth or single host attack by
using lots of small TCP segments packets. Usually large botnets are
needed for similar effect.

The rate needed for this denial of service attack to be effective is
several magnitudes lower than the usual packet processing capability of
the machine, as the attack exploits worst case behaviour of existing
algorithms.

This attack affects Linux Kernels 4.9 and later, so it affects only
SUSE Linux Enterprise 15.

Resolution

Fixes for these issues are provided as maintenance updates supplied by SUSE.

First kernel version containing the fix is 4.12.14-25.6.1.

CVE-2018-5390 is mentioned in the package changelog.

Cause

Additional Information

Workaround:

For "SegmentSmack" there is no workaround is known at this time, only

applying the patch will help.

See also: https://www.suse.com/c/suse-addresses-segmentsmack-attack/

Disclaimer

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