TCP: Linux and FreeBSD SACK and MSS Denial of Service
This signature detects attempts to exploit a known vulnerability against Linux and FreeBSD kernels. A successful attack can result in a denial-of-service condition.
Extended Description
Jonathan Looney discovered that the Linux kernel default MSS is hard-coded to 48 bytes. This allows a remote peer to fragment TCP resend queues significantly more than if a larger MSS were enforced. A remote attacker could use this to cause a denial of service. This has been fixed in stable kernel releases 4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11, and is fixed in commits 967c05aee439e6e5d7d805e195b3a20ef5c433d6 and 5f3e2bf008c2221478101ee72f5cb4654b9fc363.
Affected Products
F5 traffix_signaling_delivery_controller
References
CVE: CVE-2019-11478
Short Name
TCP:ERROR:LINUX-FREE-BSD-DOS
Severity
Major
Recommended
False
Recommended Action
None
Category
TCP
Keywords
CVE-2019-11477 CVE-2019-11478 CVE-2019-11479 Denial FreeBSD Linux MSS SACK Service and of
Release Date
12/05/2019
Supported Platforms
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3
Sigpack Version
3625
Port
TCP/0-79,81-442,444-3127,3129-7999,8001-8079,8081-65535
False Positive
Rarely
Vendors
Linux
F5
Redhat
Canonical
CVSS Score
7.8
5.0