When it comes to defending an organization against cyberthreats, knowing your enemy is not enough. Equally important is knowing what the enemy knows about you and how much you know about yourself.

That's the advice from Etay Maor, chief security officer at threat intelligence firm IntSights, in a briefing at the Black Hat Europe 2020 virtual event this week.

Increasingly, attackers have gone from breaking into a target network to simply logging into them using credentials available from a variety of sources and obtained in different ways, including social engineering, simple Web searches, and Dark Web markets, he said.

With more people working out of their homes and other remote locations because of the global pandemic, criminals have more of an opportunity to find such information, Maor noted.

Often, this data can be as simple as a default username and password combination on a router that gives them access to an employee's home network and devices connected to it. Or it could be the result of oversharing sensitive data on sites like GitHub by people working from home and looking to collaborate with co-workers on projects. Or it could be easily guessable passwords or credential data sold on the Dark Web that gives attackers access to employee devices or the enterprise network.

"Do I really know about all the devices in physical offices and home offices? Do I know if GitHub is exposing my data?" Maor said. "You can go on GitHub and run some very naïve searches and find master keys, usernames and passwords to databases, and Azure tokens," he said. Criminals are looking for this type of information because it gives them a foot in the door for launching a broader attack.

Organizations need to pay attention to knowing what an attacker might know about them, Maor says. That means thinking about all the ways criminals could collect intelligence about the organization, whether in the form of default passwords on home routers or via simple searches on public search engines like Censys. Often, intelligence that can be used in an attack is easy to find through rudimentary measures, he says.

Exacerbating the situation is the abundance of credentials and access to compromised systems that is available easily in underground criminal marketplaces, Maor said. As one example, he pointed to an advertisement that IntSights researchers recently observed on an underground forum touting domain admin credentials for a $12.5 billion company with some 33,000 employees. Among the items for sale were tens of thousands of usernames and passwords belonging to the company's employees.

In other instances, IntSights found an advertisement for a remote code execution vulnerability on a bank network being sold for $10,000, access to RDP and VNC servers selling for between $10 and $20, and access to a complete database being auctioned for $10,000, with bids being taken in $5,000 increments.

IntSights discovered access to hundreds of thousands of compromised devices belonging to individual users being sold in underground markets like Genisis Marketplace. There has been a doubling in the availability of such compromised devices since the pandemic began, Maor said.

"Every cyberbreach that has ever happened was because of one of two reasons," Maor said, quoting Frank Abagnale, whose capers as a con man in his youth landed him in prison, a career as a security consultant, and a starring role in the movie Catch Me if You Can. "Either somebody in the company did something they shouldn't have or somebody in the company didn't do something they should have."