Troj/Agent-JET changes settings for Microsoft Internet Explorer. It does this by modifying values under:

HKCU\Software\Microsoft\Internet Explorer\Security\

Troj/Agent-JET changes the following registry settings:

HKCU\Software\Microsoft\Internet Explorer\Desktop host
malicious IP address

HKCU\Software\Microsoft\Internet Explorer\Security
host
malicious IP address

More information can be found at this Sophos page.