Microsoft has published an analysis of the ransomware attacks associated with a subgroup of the Iran-linked advanced persistent threat (APT) actor Phosphorus.
Also referred to as Charming Kitten, Magic Hound, NewsBeef, and APT35, Phosphorus is known for the targeting of activists, journalists, government organizations, and various other entities, including critical infrastructure.
The activity that Microsoft analyzed is attributed to DEV-0270, a sub-group known as Nemesis Kitten that performs vulnerability scanning and other malicious network operations on behalf of the government of Iran.
According to Microsoft’s latest report, some of the group’s ransomware attacks appear to have been orchestrated for personal or company-specific revenue generation.
Redmond’s researchers say DEV-0270 exploits high-severity vulnerabilities for initial access and has been seen fast-targeting newly disclosed security bugs. The hackers also employ living-off-the-land binaries for discovery and credential access, and encrypts files using the built-in BitLocker tool.
In some of the attacks, the group was seen deploying a ransom note roughly two days after the initial compromise, and demanding $8,000 for the decryption keys. In one instance where the victim refused to pay, the adversary posted stolen data from the organization for sale.
Based on infrastructure overlaps, Microsoft believes that DEV-0270 is operated by a company that uses two public aliases, namely Secnerd and Lifeweb, both of which are linked to Najee Technology Hooshmand.
DEV-0270 scans the internet for vulnerable servers and devices and has been observed gaining initial access mainly by exploiting known vulnerabilities in Exchange Server (ProxyLogon) or Fortinet appliances (CVE-2018-13379).
Following initial compromise, the threat actor performs typical reconnaissance activities and then proceeds to credential theft and the creation of a new user account, to ensure persistence, and to escalate privileges to those of administrator, when needed.
To evade detection, the adversary turns off antivirus software, creates or activates the DefaultAccount account in the administrators or remote desktop users groups, and loads their own certificate to the local database in order to encrypt their network communications.
“The threat group commonly uses native WMI, net, CMD, and PowerShell commands and registry configurations to maintain stealth and operational security. They also install and masquerade their custom binaries as legitimate processes to hide their presence,” Microsoft added.
DEV-0270 encrypts victim data using BitLocker, which makes the infected machine inoperable. On workstations, the group uses the open-source full disk encryption system DiskCryptor, which requires a reboot to install and another to lock the infected workstation.
Given the opportunistic nature of this threat actor’s attacks, organizations are advised to patch high-severity vulnerabilities in their internet-facing assets in a timely manner, to prevent successful exploitation by this or other hacking groups.
Ionut Arghire is an international correspondent for SecurityWeek. Previous Columns by Ionut Arghire:Tags: