Prevent Sending Spam with my Yahoo Account?

Question

Today morning I found my Yahoo Mail account sent several emails with Subject re: and this body : this is crazy you should give it a look http://www.wanews15.net/biz/?news=9080205 to all my contact emails !!!
I have Eset Nod32(Up to date) Anti Virus, but it couldn't find any thing.
I've installed Microsoft Security Essential and it could find a virus. I remove it and I change my mail password.
What happened to my Yahoo Mail Account and what should I do ?

Edit :
My email password was 12 characters and I couldn't remember it , so I'm using RoboForm.
Is it possible that my Roboform password divulge. !!!

Edit 2 :
I've changed my yahoo mail password, but this morning I received Failure Notice for sending mail to some invalid mail addresses again, but there is a different this time, the sent mails didn't exist in my Sent Box. Is it a good thing or I have to do something else ?

Solution 1

I think your account has been hacked, or spammers have found out your password. It has been happening to some of my friends lately (also on Yahoo). You should change the password to your email account and scan your computer for malware using an up-to-date antivirus program. My friends have changed their password, and it hasn't happened to them since.

Also, you should be careful if you log in from another computer (a friends computer, or a public computer). That computer may have malware and it could steal your password again.

I don't think this is a case of e-mail spoofing. If it was e-mail spoofing, you wouldn't have the e-mails in your "Sent" folder.

Solution 2

The spam/virus seems effects Yahoo accounts and points to malicious sites- see http://www.mywot.com/en/scorecard/wanews15.net and http://www.mywot.com/en/scorecard/nbnews15.net

The issue also reported in http://earthchanges.ning.com/profiles/blog/show?id=6126809%3ABlogPost%3A220625&commentId=6126809%3AComment%3A220858&xg_source=activity and in http://forum.avast.com/index.php?topic=97488.0 wanews15.net - yahoo email infiltrated, spam sent to entire contact list

Solution 3

Either your account is compromised or being spoofed; as mentioned in the other answers, it's likely the former (given the presence of the spam emails in the Sent folder).

Apart from changing your password, you should also verify the password recovery options to make sure they're secure, and finally you should switch to Yahoo's two-factor authenication - it's impossible to stress how important email security is, so I'll let the venerable Jeff Atwood do it.

Finally as a side note, it appears that KMSEmulator.exe is not harmful, but is instead a hack to license Office without paying for it. Of course, this doesn't mean it isn't modified; which really just means (ethical issues aside) that if you trust people who steal software to write tools for you, then you probably are just a bit too trusting!

Comments

[user1717803]

But , if my account didn't hack , so why I have sent version of emails in my Sent Box !

[Xavierjazz]

Then somehow, someone else has access to your account. See the other answer for good advice.

[Ove]

If there are no more emails in your sent folder, it could indicate that your email address is being spoofed and they aren't sending mail from your address anymore. There's nothing you can do about that. Just keep an eye on your mailbox and your computer. You can try scanning with another antivirus to be sure you are virus-free (but don't keep more than one antivirus installed - that's bad). Also, you can try installing updates for your computer, installing newer versions of your programs (especially the web browser), and try using HTTPS for websites.