Take care to click on attachments from known contacts only.

Taking note of increasing black hat attacks, the technology service desk at the House of Representatives has warned state representatives to be very careful on the kind of e-mail they click in their inboxes.

According to its e-mail, which incidentally was forwarded to TechCrunch, due to a significant rise in ransomware attacks on congressional IT folks as well as on the House network, e-mails from YahooMail are likely to be banned.

“When a user clicks on the link in the attack e-mail, the malware encrypts all files on that computer, including shared files, making them unusable until a ‘ransom’ is paid. The recent attacks have focused on using .js files attached as zip files to e-mail that appear to come from known senders,” explains the e-mail to the less-tech savvy folk at the Congress.

Although it would be disastrous if a staff or a representative were to click on a suspicious email attachment, a spokesperson from the House Chief Administrative Officer did not confirm whether any such incident took place which led to an attack.

In addition to YahooMail, a few Google Apps were also blocked.

Of late, ransomware attacks have targeted not only the U.S. Congress but has also held computer systems hostage at a hospital in Los Angeles. In order to back control of its computer system, the hospital had to pay 40 bitcoins, around $17,000. Similarly, ransomware attacks have also targeted schools.