Hi Utu,
As always there are more than one way to solve a problem.
To patch your setup with synaptic (as root) you need to:
1) Reload package information (under the edit menu)
2) Search for "libSSL" and select (left click) on "libssl1.0.0"
3) Choose "force version" (under the edit menu) and select "1.0.1g-2 (testing)"
4) Apply button after accept & confirm the changes ("Mark", "Ok" & "Forward" buttons)
5) Check the libSSL "g" version: using: "openssl version"
OpenSSL 1.0.1c 10 May 2012 (Library: OpenSSL 1.0.1g 7 Apr 2014)
Hope this helps,
Best Regards,
Gilles

PS: This vulnerability is really an serious issue for the servers using SSL
(as the web server Apache) and which are connected to the public Internet.