"spamlet" <(E-Mail Removed)> hath wroth:
>Our pc has recently started to get locked up by what appear in the system
>log as continuous strings of attempts to connect (to the router?).
- Your "PC" is running what operating system?
- Is this the only machine on your wireless network?
- Does your WHR-G54S-1 cable router do the same thing with a wired
ethernet connection?
- How busy is your system? Does the hard disk light flash
continuously when the system locks up?
>If I am
>lucky enough to have process explorer open at the time I can kill IE and the
>network adapter (v slowly!), otherwise the plug has to be pulled.
This one?
<http://www.microsoft.com/technet/sysinternals/utilities/ProcessExplorer.mspx>
What does it say for CPU usage just before it hangs?
>Last night I thought I had better do a check with PandaActiveScan on line.
>When it finally got to the end of the scan - 'no viruses' - some 2hr later,
>the processor was locked up again, but I was lucky enough to be able to shut
>off IE and the adaptor without having to pull the plug.
My experience with virus scanners is that they catch about 90% of the
junk. The 10% remaining seem to be custom crafted remote control
programs (botnet) that are used to spew spam. These are somewhat
difficult to find but their presence can be recognized by intermittent
heavy outgoing SMTP traffic and unusual open ports. Also, look for
UPnP being on and cannot be disabled or removed.
In addition, there are root kits that are very difficult to detect.
Try this tool:
<http://free.grisoft.com/doc/39798/lng/us/tpl/v5>
>The error log showed a continuous chain of TCP/IP events for the whole time
>the pc had been on line doing this scan. These were all of the 'semaphore
>time out' type.
Thank you for severely editing all the useful information from the
system log. I'll guess that it really said:
"The semaphore timeout period has expired. . Your computer will
continue to try and obtain an address on its own from the network
address (DHCP) server."
Is this correct?
[ ] yes
[ ] no
I have some guesses but I'm lazy today. Kindly supply a single sample
message and I'll try to debug. Also, please describe this PC (CPU,
clock speed, RAM, type of HD) as this error is more common in very
slow and busy machines, particularly if they are lacking in sufficient
RAM.
>Interestingly, today, though there have been no lock ups so far, there have
>been two warnings in the error log to say that the 'TCP/IP has reached the
>security limit on the number of concurrent (incomplete) TCP connect
>attempts'.
I think your machine has been taken over by a Trojan that is running a
botnet. The symptoms are familiar familiar. My guess(tm) is that the
DHCP timeout errors are causing the semaphore errors as it trys to
change IP addresses to hide its presence. The incomplete connections
are from failed attempts to connect to various SMTP servers.
>Now, I had been looking for just such a 'limit the number of attempts
>setting', to try and stop the seize ups: why has the limit only now been
>imposed, and what does all this signify for our system? Is it likely to be
>a router/wireless problem, or is it an undetected virus or other hijack of
>some sort? (I have had some recent HiJackthis scans looked at at AumHa, but
>nothing untoward seemed to show up in the reports.)
Sigh. Get an ethernet hub, not a switch. Plug it between the cable
router and your probably infected computah. Grab a 2nd machine and
run WireShark to sniff the traffic. Look for SMTP (outgoing email)
traffic. If you find a bunch, you've been hijacked. Don't bother
trying to run Wireshark on the infected machine. Also, keep the
wireless out of the picture for now.
>Any enlightenment would be appreciated.
One must suffer before enlightenment.
>(We are using a D-Link DWL -G550+ adaptor, and a Buffalo WHR-G54S-1 cable
>router. XP Pro system.)
Ummm... thanks.
--
Jeff Liebermann
(E-Mail Removed)
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558