Samas Ransomware Uses Active Directory to Infect Entire Networks

Samas Ransomware Uses Active Directory for Reconnaissance and Spreads Across the Entire Network to Encrypt Files on Every Server and Computer

The actors behind Samas, a ransomware family that emerged about a year ago, are using Active Directory to perform reconnaissance and then infect entire networks, Javelin Networks says.

First detailed in March last year, Samas was observed employing publicly-available penetration testing tools for delivery, and its operators were said to have made $450,000 in ransom payments by December 2016. The malware has been targeting mainly the healthcare industry, researchers explain in a report SecurityWeek received via email.

Unlike most ransomware out there, which focuses mainly on encrypting local files, Samas spreads inside the entire network to encrypt files on every server and computer, the researchers say. This operation is performed in three steps: the attackers steal domain credentials, identify targets via Active Directory reconnaissance, and then move laterally through the network.

Javelin Networks, which compares this modus operandi with that of a worm, which usually spreads itself throughout the entire network, explains that the ransomware’s operators exploit a JBoss JMX-Console Authentication bypass (CVE-2010-0738) in front-facing servers to gain access to the network. Once inside the network, the attacker uses various tools to extract and steal domain admin credentials and act as a legitimate user.

The next step involves the identification of targets to encrypt, an operation performed using by querying Active Directory, “because it stores all the corporation’s information. It’s a database that stores all users, endpoints, applications, and servers,” the researchers explain. Using the CSVDE command-line Windows utility, the attacker can obtain the necessary information without risking exposure.

The attacker can then check active hosts using the PING command, and can install the malicious module on them using yet another Windows utility: PSEXEC. Because this is a legitimate, built-in command tool that IT managers use for remote control, the attack goes undetected.

“Now the worm comes in: Samas infects one computer, and then self-propagates through the network, infecting each and every endpoint and server until the whole corporation is locked down,” Javelin Networks says. Depending on the targeted organization and the industry it is part of, this can have dramatic consequences.

The researchers also point out that every organization using Active Directory can fall victim to such attacks. “This is why Active Directory reconnaissance is so powerful and effective—an attacker can learn everything about the environment by simply querying the AD,” they say.

According to Javelin Networks’ report, Samas has been mainly focused on organizations in the United States over the past year, but that entities in Europe and Asia were also targeted.

Related: Samas Ransomware Gang Made $450,000 in One Year Analysis