trojan & spyware block internet

Case Study - Trojan and spyware block accessing the Internet

Situation: Small Company has a Linksys router connecting to the Internet. In the early morning, accessing to the Internet seems to work fine. After half hour or one hour, accessing to the Internet is slow and slower. Eventually, no one in the office can access the Internet. The temporary solution is reset the router or reboot all computers.

Investigation: 1. We checked and tested all hardware connections such as NIC and cabling. They are OK and they don’t have any issues to share files and printers.

2. TCP/IP configuration looks good too. Used nslookup to check the status of DNS and it looked good.

3. Network Monitor and the log of the router listed a lot of packets sent to the router.

Resolution: Based on the Network Monitor and log, we found the problem computer with many Trojan and spyware. After we cleaned the computer and install a firewall, they don’t have the same issue any more. A happy ending!

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