Wordpress 3.1 Virus

[#1]

I inherited a website from a previous designer and I'm no expert but...
All seemed to go well for a few weeks after the CGI switchover but now Avast is detecting a virus whenever I access the Wordpress management URL (http://www.bondhaygolfclub.com/wordpress/wp-login.php)
The avast infection is
JS:Includer-BCC [Trj] at URL h_wdrsm_hikonefabebppd_com__f4i9cbk46k|{gzip}
The Wordpress dashboard seems to work OK but it displays the following in several places:
'/'); define('CONCATENATE_SCRIPTS',false); require_once(ABSPATH.'wp-settings.php'); ?>
Wordpress version is 3.1 but I am nervous about updating as last time I did this it messed up file protections & the website stopped working - I seem to recall having to run a script by Gaby to reset permissions
Is there any problem doing an auto upgrade to v3.9?

[#2]

Make sure you take a backup of the site and the db before you do the upgrade so you can restore afterwards if it breaks.  3.1 is pretty old!

[#3]

Spotted this:  https://www.youtube.com/watch?v=FjUsw4Fkxl4
No idea if it is helpful.

[#4]

Quote from: Kelly

Make sure you take a backup of the site and the db before you do the upgrade so you can restore afterwards if it breaks.  3.1 is pretty old!

I use the XCloner plugin for this.  Nice and simple to use and saves site and Database in one pass.
HTH

[#5]

Thanks MauriceC looks good

[#6]

Thankyou
Restored wordpress php files from copies & virus disappeared
Upgraded Wordpress to 3.9 automatically with no problems & done a XCloner backup
all seems OK now