Focus on Microsoft
Compromised WinXP box prob Mar 15 2008 03:11PM
Mike Moratz-Coppins (mike mikeymike org uk) (1 replies)
I am self-employed; fixing computers for customers for a living. I have
a customer's machine at home at the moment because I am stumped by a
problem on it.

I'll describe the history (AFAIK) up to this point - the customer was
running WinXP SP1 with Norton Antivirus. They noticed a problem where
it looked like lots of e-mails were outgoing, Norton detected viruses
but wasn't able to get rid of them. The customer rang Symantec support,
who spent about an hour doing remote assistance on their machine,
seemingly trying to delete the virus-infected files only to have them
recreated on reboot. The Symantec guy gave up after a while and advised
the customer that they should get hold of a WinXP CD (I'm not sure what
their intention was at this point). When the customer managed to get
hold of a WinXP CD, they rang Symantec back only to be told that they
should get someone local to deal with the problem. Then the customer
called me.

When the computer boots, it seemingly does a normal Windows boot (the
normal Windows XP progress bar (green as it is Home Edition and pre
SP2), but then the next screen it shows is saying safe mode (no reboot
in between). Standard welcome screen, but no accounts can log in ("your
account cannot log in due to an account restriction" - perhaps not
exactly word-for-word but the message looks like a genuine Windows
message rather than something crafted by a third party). This goes for
all accounts on the machine including administrator.

I tried all safe modes and 'last known good' but same result. Next I
tried the ntpasswd boot CD and reset all accounts' passwords, though
none of them said locked out/disabled etc. Boot again, no difference.

I booted off my WinXP CD into recovery console, and as the customer
mentioned boot sector viruses, for the sake of being thorough I used
FIXMBR and FIXBOOT to rewrite the boot sector and MBR. No difference to
normal Windows boot. Again in recovery console, I checked for the file
names that the customer said that Norton mentioned. Neither of them
were familiar, but I think I found one of them and renamed it to stop it
potentially executing on boot. No difference to bootup.

I guessed that the 'account restriction' might be the 'log on locally'
right but I haven't found a way of configuring this. I tried renaming
logonui.exe to cmd.exe but that command prompt won't let me run any
other executables (not enough quota message) such as ntrights.exe. One
possibility I can think of is to set up a LAN with DHCP, put my laptop
on it and the machine in question and try to do ntrights over the
network but I would have thought that the firewall on that machine would
stop that attempt. Of course I could be barking up the wrong tree with
this overall 'account restriction' theory. I also tried having
REGEDIT.EXE run in the place of LOGONUI.EXE but it errors saying I
didn't supply it with an argument. Eventually it gives up trying to run
it and goes to the winlogon classic UI, which unsurprisingly gives me
the same account restriction error.

The other problem I have noticed is that I saw a few iffy-looking
services in recovery console using LISTSVC but I can't configure the
service startup type as the command complains that there isn't a
CurrentControlSet key.

That last problem makes me think that this and the 'account restriction'
were inadvertently caused by Symantec support, perhaps one of their
removal utilities (which I've noticed one or two on C drive) has done
some damage. My only other theory is that some over-zealous malware
writer has designed some sort of self-destruct system but I can think of
more effective ways of achieving such an end and overall I think this
theory is rather alarmist.

I've mounted the disk on my machine and virus-scanned it. It has
removed a few assorted virus-infected files and cleaned up a couple of
others (such as lsass.exe - not misspelt), but the machine still doesn't
start. I've backed up the customer's data and I have got the customer's
consent to nuke the installation but I would prefer not to if it isn't
necessary (and learn from this experience), though of course I don't
want to spend a huge amount of hours on this problem only to fall back
on the repair-reinstall/clean-install option.

If anyone has any ideas I would much appreciate hearing them!

Mike Moratz-Coppins
mike (at) (dot) uk [email concealed]

[ reply ]
RE: Compromised WinXP box prob Mar 17 2008 05:34PM
Devin Ganger (DevinG 3sharp com) (1 replies)
RE: Compromised WinXP box prob Mar 17 2008 05:41PM
Robert S. Slifkin (rob SLIFKIN NET)


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