Ransomware attacks have been rife in 2021, with the increase in attacks seen in 2020 continuing throughout 2021. The number of attacks conducted in 2021 has been staggering. There were more attempted ransomware attacks in the first 6 months of 2021 than there were in all of 2020, according to one report.
Ransomware-as-a-service (RaaS) operations that were active throughout 2020 have increased their attacks, and while some RaaS operations have been shut down, attack volume is showing no sign of reducing. There is also a new ransomware threat to defend against. The Federal Bureau of Investigation (FBI) has issued a warning about a new ransomware threat actor that has been particularly active in the United States. The group, known as OnePercent, has been using its ransomware to attack U.S. businesses since at least November 2020, according to a recent FBI Flash Alert. The group is known to use the legitimate penetration testing tool Cobalt Strike in its attacks, and prior to using their OnePercent ransomware variant to encrypt files, the attackers exfiltrate sensitive data from victims’ systems. A ransom demand is issued for the keys to decrypt files and to prevent the publication of the stolen data on the group’s data leak sites on the TOR network and the publicly accessible Internet.
Like many ransomware gangs, the initial attack vector is phishing emails. Phishing emails are sent to targeted organizations that have malicious .ZIP email attachments which contain Word documents or Excel spreadsheets with malicious macros that deliver the IcedID banking Trojan. The Trojan downloads and installs Cobalt Strike on endpoints to allow the attacker to move laterally within victims’ networks to compromise as many devices as possible. The group is also known to use PowerShell, Mimikatz, SharpKatz, BetterSafetyKatz, and SharpSploit, and Rclone for data extraction.
The attackers are known to take their time within networks to identify and steal critical data. In attacks reported to the FBI, the group has spent up to a month from the initial compromise to the deployment of OnePercent ransomware. During that time, considerable volumes of data are exfiltrated. The ransomware itself encrypts files and uses a random 8-character extension for encrypted files.
As is now the norm, there is no fixed ransom payment. Victims are required to make contact with the attackers to receive ‘technical support’ recovering their files and to discover how much needs to be paid for the decryptors and to ensure data deletion. If the ransom is paid, the attackers say they will deliver the decryption keys within 48 hours. The threat group is also known to contact the victim by telephone using spoofed telephone numbers to pressure victims into paying by threatening to publish the stolen data. The group has also threatened to sell the stolen data to the Sodinokibi ransomware gang to list for sale at a public auction.
Since the group uses phishing emails as the initial attack vector, preventing those messages from reaching inboxes is the best defense against attacks. That requires an advanced spam filtering solution such as SpamTitan. It is also recommended to configure emails to display a warning when they are received from a sender that is outside the organization.
It is also important to follow cybersecurity best practices such as network segmentation to limit the potential for lateral movement, to audit user accounts with admin privileges and restrict their use as far as possible, and to configure access controls using the principle of least privilege. All critical data should be backed up offline on an external hard drive or storage device that is disconnected once the backup has been performed. Backups should also be tested to make sure file recovery is possible.
While the OnePercent ransomware gang is only known to use phishing emails as the attack vector, other methods of attack may also be adopted. It is therefore recommended to ensure that remote access and RDP ports are disabled if not used, to monitor remote access/RDP logs, to keep computers and applications up to date and to apply patches promptly, and to ensure that strong passwords are set and multi-factor authentication is implemented.