Phishing Attack Ends in Ryuk Ransomware Infection for City of Durham, NC

The City of Durham and the County of Durham in North Carolina have experienced a ransomware attack that has crippled both. The attack ‘started’ on March 6 in the late evening, which is common for ransomware attacks. Most take place in the evening and over the weekend, when there is less chance of the file encryption being detected.

Two separate attacks occurred simultaneously. Fast action by the IT department helped to contain the attack, but not in time to prevent approximately 80 servers from being infected. Those servers were encrypted and need to be rebuilt and approximately 1,000 computers had to be re-imaged.

There are many ways that cybercriminals gain access to business networks to deploy malware, but email is the most common attack vector. Most cyberattacks start with a phishing email and this attack was no different.

Ryuk ransomware was used to encrypt files on the network in order to extort money from the city and country. A ransom demand is issued which, depending on the extent of encryption, can range from several thousand dollars to several million. This phase of the attack is the most visible and causes the most disruption, but the attack actually started much earlier.

Ruyk ransomware is delivered by the TrickBot Trojan, an information stealer turned malware downloader. One installed on a networked device, the TrickBot Trojan performs reconnaissance, moves laterally, and installs itself on other computers on the network. Once all useful information has been found and exfiltrated, a reverse shell is opened and access to the system is given the ransomware operators. They will then move laterally and download their ransomware payload onto as many devices as possible on the network.

TrickBot downloaded by Emotet malware, a notorious botnet and Emotet is delivered via email. The Emotet campaigns used a combination of Office documents with malicious macros that download the malware payload and hyperlinks to websites where malware is downloaded. TrickBot may also be delivered directly through spam email. This Trio of malware variants can do a considerable amount of damage. Even if the ransom is not paid, losses can be considerable. The Trojans can steal a substantial amount of sensitive information including email credentials, banking credentials, tax information, and intellectual property.

In this case, seven computers appear to have been compromised in the first phase of the attack as a result of employees responding to phishing emails.

The key to blocking attacks such as this is to have layered defenses in place that are capable of blocking the initial attack. That means an advanced spam filtering solution is required to block the initial phishing emails and end users must receive regular security awareness training to help them identify any malicious emails that arrive in their inboxes. Multifactor authentication is needed to prevent stolen credentials from being used to access email accounts and endpoint security solutions are required to detect malware if it is downloaded.

To find out more about protecting your systems from phishing and malware attacks, and how a small per user cost per month can prevent a hugely expensive cyberattack, give the TitanHQ team a call today.