Wednesday, August 17, 2016

TCP Flaw Workaround Patch for Gigastrand OS

A flaw for Linux devices – including Gigastrand OS – has been discovered as detailed at Hacker News

Researchers have uncovered a serious Internet flaw, which if exploited, could allow attackers to terminate or inject malware into unencrypted communication between any two vulnerable machines on the Internet.

The vulnerability could also be used to forcefully terminate HTTPS encrypted connections and downgrade the privacy of secure connections, as well as also threatens anonymity of Tor users by routing them to certain malicious relays.

The flaw actually resides in the design and implementation of the Request for Comments: 5961 (RFC 5961) – a relatively new Internet standard that’s designed to make commonly used TCP more robust against hacking attacks.

Manual patch

You can add the following line to /etc/sysctl.conf (right click on sysctl.conf>Root Actions>Open as Text)

net.ipv4.tcp_challenge_ack_limit = 999999999

Then open a terminal and execute

sudo sysctl -p

and it will do the same thing as the patch below.

Automated Patch: Download – tcpatch.tar.gz

The above patch automates the process and contains a workaround implementation of a modified sysctl.conf that should protect Gigastrand OS and other Linux PCs from attack while a system patch is being developed. Instructions are below.

Chrome and Firefox will download the GsNVR.tar.gz file to Computer>Downloads (/home/user/Downloads).

  1. Extract the downloaded file with Ark to your home folder (/home/user) also called Computer

  2. Right-click on the file and select Properties

  3. Click on the Permissions tab and select Is Executable

  4. Click Ok

Now we are ready to install.

  1. Right click in a blank area and go to Actions>Open Terminal Here

  2. type ./ or sh

  3. Your output should look like this:


tcpatch output screen

TCP Flaw Workaround Patch for Gigastrand OS

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