Report: Rise Of “Conversation-Hijacking” Phishing Attacks Threatens Businesses

Because the technique involves impersonating a trusted employee, the hacking method has the potential to be unusually effective.

• By Haley Samsel
• Jan 17, 2020

There has been a significant increase in the number of hackers implementing “conversation-hijacking” attacks to trick employees into installing malware, transferring money or disclosing their passwords, according to a new report from Barracuda Networks.

The phishing technique involves a hacker infiltrating real email threads between company employees by taking over accounts with previously stolen login credentials, perhaps bought through the dark web, according to ZDNet. After getting into the email account, attackers will impersonate the worker and attempt to extract information from their colleagues.

In an analysis of 500,000 emails, Barracuda found that conversation hijacking increased by over 400 percent between July and November 2019. The attacks are still relatively rare compared to traditional phishing attacks, which typically involve emails asking employees to click a link that installs malware on their devices and allows the attacker to gain access to a network.

But cybersecurity experts are concerned about the attacks because of how effective the technique could potentially be on gaining access to financial accounts or other sensitive information. Hackers will spend time on reading through conversations, researching victims and impersonating the way they write, according to Olesia Klevchuk, senior product manager for email security at Barracuda.

“These attacks are highly personalized, including the content, and therefore a lot more effective,” Klevchuk told ZDNet. “They have the potential of a very large payout, especially when organizations are preparing to make a large payment, purchase or an acquisition.”

Workers are more likely to believe the impersonation than an email from a random address asking them to click a link, according to Klevchuk. But the attacks are also not impossible to spot.

Attackers usually don’t use the actual compromised account to send the phishing message because the actual user can see if an email has been sent from their account. Instead, the hacker will try to impersonate the employee’s email domain with a technique called “typo squatting” that changes one or two characters to trick recipients into thinking the email is the real deal.

This makes it crucial for recipients to check the email address and domain if they are suspicious that their colleague did not send an email demanding account information or payment. In addition, employees should reach out directly to the employee through another contact method -- in person, by phone or through another email -- to check if they sent the email, according to ZDNet.