SimplerCloud Pte Ltd

This advisory is provided as a courtesy.

We would like to bring to your attention that a new security vulnerability found on Linux kernel before 4.7, specifically on the net/ipv4/tcp_input.c module, which does not properly determine the rate of challenge ACK segments. This makes it easier for man-in-the-middle attackers to hijack TCP sessions via a blind in-window attack. This security vulnerability has been assigned common vulnerability and exposure code: CVE-2016-5696.

Impact

The vulnerability allows a MITM (man-in-the-middle) attacker to hijack TCP sessions via a blind in-window attack, resulting in the attacker to be able to break the connection, and in certain situation, to perform data injection attacks.

Affected OS

Most of the newer Linux operating systems, such as Ubuntu 14/16 and CentOS 6/7 are affected by this vulnerability. This includes, but not limited to:

- Ubuntu 12
- Ubuntu 14
- Ubuntu 16
- CentOS 6
- CentOS 7
- Debian 7
- Debian 8

How to Fix the Problem

Currently Linux kernel patches are still being developed to address the issue. Once the patches are out, you will be able to resolve the problem by installing the latest patches on your operating system.

- On Ubuntu/Debian system:

apt-get update
apt-get dist-upgrade

- On CentOS system:

yum update

More information

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-5696
https://access.redhat.com/security/cve/cve-2016-5696
https://people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-5696.html
https://security-tracker.debian.org/tracker/CVE-2016-5696

Request Assistance

The patches are not out yet, however once the patches are out, we can perform the patch installation for you at a one-time discounted fee of $10. Please submit your order at Order -> Additional Services -> Vulnerability Fix - LINUX & WINDOWS: Linux Kernel "Use-After-Free", OpenSSL, GNU C Library and Poodle SSLV3 Vulnerability - $10.

Or please first open a support ticket and give us the hostname, IP address and OS template. You can find this information on your servelet's control panel.

For example:

Hostname: test-dd
IP Address: 103.25.202.81
OS Template: CentOS 6.5 (64-bit) 20140123a

Thank you.