Cisco Internet Protocol (IP) telephones can be hacked and used to listen to your phone conversations from anywhere around the world, according to researchers at Columbia University working with the U.S. Defense Department. The researchers claim that they can use a small device pre-loaded with software to rewrite the telephone's software in a matter of seconds. All you need is physical access to the telephone and a few seconds to hack it. Also, it only takes one hacked telephone to listen to conversations on all the other IP telephones on the company's network.
Government and large corporations are at high risk of their IP telephones being hacked. These entities have a large number of IP phones which an employee can hack or an outsider could trick an employee into clicking on an e-mail attachment that contains a virus, infect the employee's computer and then use that same computer to attach IP phones inside the company's network.
Also, a phone technician or someone posing as one, can hack these IP phones because that person would have access to the phones.
Here is the device that can be used to hack a Cisco IP phone

All you have to do is to plug the device into the IP phone port. The phone will need internet access.
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