How are these trojans getting in???

Posted on 2004-03-20
Last Modified: 2013-12-04

Since the 13th of March I have been geting trojans detected by Norton AV 2004's auto protect. The trojans seem to arrive at random intervals and vary. The first one was W32.Welchia.B.Worm. Then 6 trojan droppers over the next two days. Backdoor.SDBot.Gen. W32.Randex.AR. Then Bloodhound detected two unknown threats. Then a couple of IRC Trojans and BAT.Trojans.

Sounds to me like someone is determined to get in my system or some program on my machine is downloading trojans. I've looked thoroughly at running processes and cant see anything unusual. Startup areas seem fine too. I have Sygate Personal Firewall enabled and presently the portscan on my machine shows i have stealthed all ports except UPnP(intentional for MSN messenger Aud/Video). Another open port is the telnet port that my router modem stupidly leaves open even when WAN side telnet server is disabled. I have changed the port number of the telnet server in the router settings for security.

Im running XP Pro SP1a.

How on earth could they be getting in?
Question by:ironbut
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LVL 11

Expert Comment

ID: 10641936
Have you checked Sygate's logs? Does NAV give any other info? Could it be email?

Author Comment

ID: 10641971
I have cleared the security log recently but Syagate reports port scans at least every few days from various people. I usually dismiss them as casual hackers because of their frequency and nothing bad has been happening up till the 13th. I have Outlook Express always running and checking emails every 3 mins. Outlook is always running too, but not used as an email program. Norton scans any incoming / outgoing emails and i barely ever get spam.
LVL 12

Expert Comment

ID: 10641973
List of known Trojan/Backdoors and the TCP/UDP ports on which they operate

Many Regards
Jorgen Malmgren

:o) Your brain is like a parachute. It works best when it's open
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Expert Comment

ID: 10641983
Sygate is not the only scanner to tell you what to do. Different scanners maybe do a different work.

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LVL 12

Expert Comment

ID: 10641996
>I have been geting trojans detected by Norton AV 2004's
>How on earth could they be getting in

Are they getting in, or are you only getting alerts from NAV that they try to get in ?

If so, you can't stop them from trying

Author Comment

ID: 10642002
No. They are getting in. I have had some sort of IRC virus placed in my windows\system32\dhcp folder and trojans in my system32 folder.
LVL 38

Accepted Solution

Rich Rumble earned 125 total points
ID: 10642640
XP- the classic fix for reinfections is the System Restore feature:
Turn it off, then clean your PC with a nice through scan with the latest dats... unplug the network cable for now... then make sure your scanning within Zip and other compressed files, and scaning ALL file types on ALL drives.
After your pretty sure you've cleaned the pc, reboot, scan again. Then if all is clear, enable the windows XP firewall, it does a very nice job of blocking incoming connections. If you want more configurable firewall, get ZoneAlarm it is free and does a fine job at Firewalling- it has the added benefit of process locking/blocking... meaning, if you got infected somehow, and a new process called viri.exe tried to run, ZA would ask you if you would like to allow Viri.exe to access the internet- you would say "NO, and remember this response the next time"- then you can spend your time finding out how to clean that program off, without having to worry about it doing any damage. The process locking/blocking has an advantage over AV, in that it doesn't need a definition other than the name, and checksum of the program... ZoneLab's guys are smart... if you got a virus called system.exe and had permitted the ligit program to access the internet before... this new system.exe wouldn't be allowed because it's file size is different.

Also, use ad-aware or equivilent spy-ware finding program to clean your machine also- in addtion to AV...
Turn off these services:
Remote Registry
Remote Desktop ...
Server (only disable this one if you do not connect to other windows machines, or share files or folders)
Then change your passwords as you never know... Rdesktop is a very easy way into XP machines...

Assisted Solution

Joseph_Moore earned 125 total points
ID: 10643035
Something else to keep in mind is that if you are getting reinfected by Welchia (a Blaster worm variant), then you need the MS03-039 patch. Go here for info:

This patch will fix the DCOM/RPC vulnerability that exists. With this being unpatched, it is possible to connect to your system, trigger the exploit, and execute something. that is how Welchia keeps getting in.

You need to patch your system to stop this.

Author Comment

ID: 10643566
Ive got sygate personal firewall, which does all the stuff you mentioned. One thing that shocked me was that remote registry service was started, so i have disabled it. I have just turned off Sys Restore and will try a full scan in safe mode later. I am on a lan so Server cant be stopped.

Im assuming i already have that patch as i regularly use windows update, but i will see if i can download it anyway.

Btw some of the files i found in windows\sytem32\dhcp...

--- cool.vsx ---

%many 44
%infecttime Tuesday 18/11/2003 21:20:06
%nnick []guio17
%fnick 8
%1p1 213.33.11.*

--- pamella.jpg ---

Fingers crossed.
LVL 11

Expert Comment

ID: 10643790
Cool.vsx is created by the Worm_Kines.D (
Not sure about pamella.jpg, but I doubt its good.

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