'Tox' Offers Ransomware As A Service

The ready availability of packaged easy-to-use malware kits in underground markets has significantly lowered the barrier to entry for aspiring cybercriminals, and now they have one more tool option.

A researcher at Intel's McAfee Labs has unearthed what amounts to a ransomware-as-a-service kit for building and deploying ransomware. Dubbed "Tox," the kit requires very little technical skills to use and appears designed to let almost anyone deploy ransomware in three easy steps.

Jim Walter, the director of advanced threat research for Intel Security said he stumbled across Tox earlier this month when sifting through a stream of  dark web data. In the days since then, the site hosting the malware kit has been updated with a new FAQ and design. But the core functionality has remained the same, Walter said in a post.

Tox is free to set up and use. But the catch is that the site hosting the kit retains 20% of any ransom that is paid by victims to attackers who use the software.

Tox runs on the Tor network and is set up to receive payments via Bitcoin, allowing for some degree of anonymity for the attackers, Walter said. The malware works as advertised, so people can use it to essentially encrypt data on victim computers and demand a ransom in return for unencrypting it.

"Out of the gate, the standard of antimalware evasion is fairly high, meaning the malware's targets would need additional controls in place," such as host intrusion prevention, whitelisting and sandboxing to catch or prevent Tox, Walter wrote.

What makes Tox interesting is just how easy it is for almost anybody to use it. Would-be cybercriminals have to simply register with the site, enter the ransom amount they want into the specified filed, submit a "cause" for launching the attack, and correctly guess the CAPTCHA.

The three-step process creates a malicious 2MB executable file disguised as a screensaver file, which users can distribute to victims of their choice.

When the malware is executed, it downloads the CURL command-line tool and a TOR client on the infected system. Once the malware encrypts all the contents on the target computer, it serves up a standard ransomware message instructing the victim to pay a fine in Bitcoins for the data to be unencrypted.

A screenshot of the message posted on Walter’s blog shows it provides detailed information on how the victim can buy Bitcoins and where to submit the payment. It tells victims to expect their data to be decrypted in about two hours after ransom payment typically, and provides a link where they can get help if the data is not decrypted after the ransom has been paid.

"You can also spam this mailbox with useless stuff or wishing me death, so that mail sent from real people who actually need help won't be read," the message informs victims.

The Tox site monitors all the installs and any money paid by the victims. In order to receive money, the Tox user has to supply a receiving Bitcoin address.

From a technical standpoint, Vox's code appears to lack much sophistication and efficiency and contains several identifying strings within the code, McAfee's Walter said.  But it is easy to use and fully functional. Expect to see more sophisticated encryption and evasion techniques used in similar tools going forward, he said.