Possible virus on iPhone Yahoo account

In order to enable iCloud, I had to use my yahoo account given my regular gmail one is not accepted. Consequenty I configured it on my iPhone and soon found appearing in my contacts a huge list of entries that I did not see in my web yahoo account.

What is worse is that "something" started to spam all those addresses with assorted messages like the following one:

or

Hey Friend...

i can't imagine doing anything else ever again

http://mrcleancarwash.com/CraigRichardson53.html

c ya.

Both my pc at work and my personal mac were off at that time and so they could not be the culprits: moreover neither of them have a configured yahoo address neither in Apple Mail nor Thunderbird.

I contacted yahoo that answered me as follows:

Hello,

Thank you for contacting Yahoo! Customer Care. Before I go into

addressing your concern, I'd like to first apologize for the delay in my

responding to your inquiry. We are committed to answering your questions

as quickly and accurately as possible. However, we are currently

receiving unusually high volumes which caused the delayed response.

I have investigated the issue you reported, and it appears that the

problem with your account is now resolved. I apologize for any

inconvenience this has caused. Please be assured that we'll do our best

to prevent such problems in the future.

If you continue to experience difficulties and you are still unable to

send emails 24 hours after receiving the error message, let us know so

we may further assist you. In your response please include the time and

date of the last error message received.

In the meantime, we appreciate your patience and your continued support

of Yahoo! Mail. Your reports and comments are always important to us as

we strive to be the best email service on the planet.

Thank you again for contacting Yahoo! Mail.

Regards,

But, nothwithstanding their reply, the messages kept on being sent.

As a preacutionary measure I removed all those mysteriously appeared yahoo contacts from my iPhone, just leaving myself to check what happens. Still I am very worried at a number of different levels: both for me, my phone and for Apple in general.

Thanks for your answer,

Fabrizio