Yahoo email hijack

[Barnacle_Bill]

Yesterday my Yahoo email account was hacked into and spam sent to everyone in my address book as though I had sent it. My immediate response was to virus check my whole PC and Spybot it as well. But thinking about it, is it likely to be malware on my PC doing this, given that this is a web-based email account? Additionally, there were no entries for the spam in my "Sent" folder so it was not as if something had taken over my computer and pretended to be me to send all the spam. And yet my address book (contacts list) was used to target the spam.
Of course it has proved impossible to ask a carbon-based organism at Yahoo the same question.

[MarkRae]

Could easily be... Some malware captures logins to such sites and then use these to log in and send email etc.

Alternatively, how "guessable" was your Yahoo password? Did anyone else know it? Could anyone have seen you type it in? Have you used it in an Internet café lately? Or somebody else's computer?

[Barnacle_Bill]

Hi again Mark,
The password's not very guessable but it could have happened with one of those programs which do dictionary searches I suppose. Another possibility is that I joined LinkedIn recently - a networking site - and provided my email password while doing a contacts synchronisation.
But however it happened, if someone/something actually logged in to my account and sent email, I would have expected the messages to show up in my "Sent" folder

[MarkRae]

Think about it - if you hacked into someone else's Yahoo account with the purpose of sending spam, what's the first thing you'd do after the spam was sent? Well, if you had any sense, you'd clear out the Sent Items folder, wouldn't you?

[Barnacle_Bill]

Er.. why on earth would I bother?