February 28, 2021 By David Bisson 2 min read

Cyber criminals are using Voice over Internet Protocol (VoIP) platforms to launch vishing attacks against employees worldwide, the FBI warned on Jan. 14. 

Vishing means ‘voice phishing,’ an attack in which threat actors use phone calls instead of emails. Their goal: to try to trick the person on the other end into allowing access to their accounts. Vishers may try to convince employees to visit a website designed to steal their credentials, the FBI warned. Success gave the attackers all they needed to move deeper into the victim’s network.

Read on to learn more about this campaign as well as how to avoid vishing attacks in general.

What is Vishing?

Those responsible for January’s vishing attempts started as far back as December 2019. But, the latest cases were particularly noteworthy. The attackers targeted all employees, not just those in top roles who might have greater access. Once the users of VoIP platforms picked up the phone, the attackers tried to trick them into authenticating themselves on a phishing website. This site then stole their employee username and password.

With those details, the attackers could gain greater access to a targeted group’s network by elevating their privileges. They could then use that access to cause even greater financial damage.

In one instance, vishers located an employee through a company’s chatroom, the FBI said. Then, they used a fake VPN login page to steal their credentials. The attackers authenticated themselves as the employee. Using this false persona, they found another employee who could implement username and e-mail changes. Next, they used a chatroom messaging service to steal that person’s details, too.

A Look Back at Other Recent Vishing Attempts

The campaign described above wasn’t the only time that vishers made headlines in the past few months.

Threat actors registered domains and created phishing pages to impersonate organizations’ virtual private network (VPN) login pages, KrebsonSecurity revealed in August 2020. Those portals even came equipped with the ability to steal employees’ multifactor authentication (MFA) codes so the attackers could compromise their victims’ accounts and mine the affected organization’s databases for customer information.

Around the same time, Scam Detector warned of malicious actors using VoIP number and computer pots to impersonate the U.S. Internal Revenue Service. With that disguise, the attackers threatened that they would file a lawsuit against the recipient unless they agreed to pay a fake outstanding tax bill and hand over their payment information.

How to Avoid VoIP Attacks

The FBI made several suggestions as to how employers can avoid falling victim to a vishing attack.

1. Consider putting MFA in place on all employee accounts. Doing so will help to prevent threat actors from getting the first foothold on your network.

2. Use the principle of least privilege. This makes it harder for attackers to elevate their privileges on a compromised account to get greater access to the network.

3. Segment the network and deploy monitoring solutions within each of those segments to watch for signs of potential account compromises. With these tactics you can decrease the chance of VoIP scams opening a door into your network. 

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