Do I need to change my password after finding a virus?

by techtiptom

Originally posted on wibc.com on 07/30/2012

From a listener:  When I opened Internet Explorer, a message popped up from my anti-virus program (AVG Free) advising that Trojan Horse PSW.Lineage.BKG was detected in a .dll file and a bin file of the Ask Toolbar in Program Files. Two options were offered: “heal” or “move to virus vault.” Unclear of what the difference is, I chose “heal” and the Ask file along with a restore point were moved to the AVG virus vault. Several follow up scans in safe and regular mode as well as an online Kaspersky scan showed no malware.

 

Research yielded no info about PSW.Lineage.BKG, even on the AVG site, but other PSW.Lineage Trojans are mentioned online. It seems that this Trojan attempts to steal passwords, and BKG “may” be an abbreviation for “banking”. I do not do online banking but do use my credit card on the Internet. I use Windows firewall and an Actiontek modem/router.


Is it necessary now to change all my online passwords or can I feel reasonably sure that this has been taken care of?

The short answer is probably not … but. The problem is that we don’t actually know exactly what happened, and the not knowing means that there’s some risk.
When your anti-malware software detects and removes an infection, it can happen at either of two times:

  • Before the malware had a chance to actually execute and infect your machine
  • After the malware had been executed and had infected your machine

The problem is, that based on your question, I can’t honestly tell which it was. In fact, it’s even likely that depending on exactly what your anti-malware software reported, you might not be able to tell which it was either. The difference, of course, is that if the malware is caught before infection, you’re likely quite safe. If caught after infection … well, it may be too late.

Now, the reason I waffle at all is that most real-time scanners will fall into the former category, catching things as they arrive (in “real time”), and blocking them from ever infecting your machine. Since you indicate that this message has popped up in Internet Explorer, that’s typically the result of a real time scanner.

On the other hand, you indicate that it was “detected in a .dll file or a bin file of the Ask Toolbar in Program Files.” That typically means that the infection is already in place, since the infected file appears to have been installed into its working location. Thus we’re left not really knowing exactly what happened. And as a result we don’t know exactly what the risks are that you’ve been exposed to.

I think you can guess where I’m headed with this.

In the words of Dirty Harry: “… you’ve got to ask yourself one question: Do I feel lucky?” In your shoes … I’d change my passwords. It’s an inconvenience, perhaps, but better safe than sorry.

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