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What
is a Trojan Horse?
Named after
the famous Wooden Horse used by the Greeks to
conquer the city of Troy, these programs basically invade your PC
disguised as a piece of desirable software. Often hidden inside
the installation routines of pirate software downloaded from the
internet they install themselves at the same time as the actual
application and modify your system settings to ensure they are automatically
run every time your PC is started up.
Trojan
horses themselves seldom damage the system they infect, preferring
to silently allow attackers to access your machine over the internet
and do almost anything from stealing your files through to destroying
your hard disk. Because they normally rely on an internet connection,
PC's with cable modems or other always-on connections are especially
vulnerable if infected with a trojan horse.
Regular
users of IRC need to be especially wary of receiving trojan horses
in files they download from other users. These often exploit bugs
in the Windows operating system to make themselves appear to be
harmless picture, text or zip files when in reality they are executables
which will install a trojan horse on your system if run.
How
can I tell if I'm infected?
By far the best way is to run a scan of your system with a suitable
tool.
Antivirus software will detect and often remove most trojans horses
as well as viruses but for more stubborn problems a dedicated anti-trojan
package may be needed. We recommend Swat-IT from Lockdown Corp.
which will detect and remove almost all known trojan horses. As
with virus scanners, it needs to be kept updated as new trojans
are being released all the time.
Other
telltale signs include :
- Unexplained
activity (windows opening or closing on their own, mouse moving
on it's own, cd-rom opening or closing etc.)
- Unusual
message boxes or strange error messages.
- Outlook
or outlook express taking a long time to close or seeming to hang
when you preview a specific message (can indicate an email worm).
- Corrupt
files.
- Unknown
programs in the task list (NT, Win2k)
- Alerts
from your firewall about OUTBOUND communication from an unusual
source.
RESOURCES:
Detecting and Removing Trojan Horses
Recovering from a System Compromise
Securing your system against Viruses and Trojans
Lockdown Corp's Swat-IT Trojan Scanner
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