Quick fix for the OpenSSH security bug

15 Jan

This week a pair of critical security vulnerability found in the OpenSSH client that can allow an attacker to read the user’s computer memory, possibly leaking private keys. CVE-2016-0777 and CVE-2016-0778

ArsTechnica writes,

The vulnerability resides only in the version end users use to connect to servers and not in versions used by servers. A maliciously configured server could exploit it to obtain the contents of the connecting computer’s memory, including the private encryption key used for SSH connections. The bug is the result of code that enables an experimental roaming feature in OpenSSH versions 5.4 to 7.1

So if you can update your computers for the latest security patches. If you’re on a Mac you’ll have to wait for Apple to issue a software update to resolve this issue. This is the same for Windows, and other linux operating systems.

If you use Terminal or other SSH client you can manually update your computer by setting the UseRoaming parameter to no in your .ssh/config file.

Open your terminal and enter the following to add

UseRoaming no

to your config file:

echo -e 'Host *\nUseRoaming no' >> ~/.ssh/config

That should prevent this issue from happening. Hopefully the OS vendors will issue their security updates soon.

For more information you can read the ArsTechnica article, Bug that leak crypto keys just fixed in widely used OpenSSH

If you want a more technical viewpoint, check this page OpenSSH: client bugs CVE-2016-0777 and CVE-2016-0778

Leave a Reply

Your email address will not be published. Required fields are marked *