The Rockingham school district in North Carolina discovered Emotet malware had been installed on its network in late November. The cost of resolving the infection was an astonishing $314,000.
The malware was delivered via spam emails, which arrived in multiple users’ inboxes. The attack involved a commonly used ploy by cybercriminals to get users to install malware.
The emails appeared to have been sent by the anti-virus vendor used by the school district, with the subject line ‘incorrect invoice’ and the correct invoice included as an attachment. The emails were believable and were similar to many other legitimate emails received on a daily basis.
The emails asked the recipient to open and check the attached invoice; however, doing so would see malware downloaded and installed on the email recipient’s computer.
Soon after those emails were received and opened, staff started to experience problems. Internet access appeared to have been blocked for some users. Reports from Google saying email accounts had been shut down due to spamming started to be received. The school district investigated and discovered several devices and servers had been infected with malware.
Emotet malware is a network worm that is capable of spreading across a network. Infection on one machine will see the virus transmitted to other vulnerable devices. The worm drops a type of banking malware on infected devices that is used to steal victims’ credentials such as online banking details.
Emotet is a particularly advanced malware variant that is difficult to detect and hard to remove. The Rockingham school district discovered just how problematic Emotet malware infections can be when attempts were made to remove the worm. The school district was able to successfully clean some infected machines by reimaging the devices; however, the malware simply re-infected those computers.
Mitigating the attack required assistance from security experts, but even with expert help the recovery process is expected to take up to a month. 10 ProLogic ITS engineers will spend around 1,200 on site reimaging machines. 12 servers and potentially up to 3,000 end points must be reimaged to remove the malware and stop reinfection. The cost of cleanup will be $314,000.
Attacks such as this are far from uncommon. Cybercriminals take advantage of a wide range of vulnerabilities to install malware on business computers and servers. In this case the attack took advantage of gaps in email defenses and a lack of security awareness of employees. Malware can similarly be installed by exploiting unpatched vulnerabilities in software, or by drive-by downloads over the Internet.
To protect against Emotet malware and other viruses and worms layered defenses are required. An advanced spam filtering solution can ensure malicious emails are not delivered, endpoint detection systems can detect atypical user behavior, antivirus solutions can potentially detect and prevent infections, while web filters can block web-based attacks and drive-by downloads. End users are the last line of defense and should therefore be trained to recognize malicious emails and websites.
Only a combination of these and other cybersecurity defenses can keep organizations well protected. Fortunately, with layers defenses, it is possible to avoid costly malware and phishing attacks such as the one experienced by the Rockingham school district.