My client system has been compromised and hacked.
My client is using wWindows 7 and Outlook Express 2007 for email communication.
The Email ID of my client is from a Yahoo Small Business account.
My client is using licenced antivirus from QuickHeal Total security.
Now my clients email is, say
firstname.lastname@example.org and buyers email say
Now, the hacker has created 2 separate email IDs:
every email getting passed from both sides goes to hacker then hackers feels the email should not be stopped passed to client and his buyers from above 2 email addresses.
These fake emails pop up in "reply email" when my client or his buyer clicks "reply" for email in Outlook Express. Since the IDs looks so similar and because of regular communication, the hacker took advantage of this.
This happend with my clients and his 4 buyers and the hacker took advantage of this and got funds transferred to his UK accounts by modifying the communication in between.
Please suggest what can be done to secure system and get rid of this problem permanently and how to trace where the whole system has been compromised.