Cybersecurity researchers have disclosed a new variant of the AvosLocker ransomware that disables antivirus solutions to evade detection following breaching concentrate on networks by taking gain of unpatched security flaws.
“This is the 1st sample we noticed from the U.S. with the capacity to disable a protection option utilizing a legit Avast Anti-Rootkit Driver file (asWarPot.sys),” Craze Micro scientists, Christoper Ordonez and Alvin Nieto, stated in a Monday examination.
“In addition, the ransomware is also capable of scanning a number of endpoints for the Log4j vulnerability (Log4shell) using Nmap NSE script.”
AvosLocker, one particular of the newer ransomware people to fill the vacuum remaining by REvil, has been joined to a selection of assaults that targeted critical infrastructure in the U.S., together with monetary solutions and authorities amenities.
A ransomware-as-a-support (RaaS) affiliate-dependent team initially noticed in July 2021, AvosLocker goes past double extortion by auctioning details stolen from victims really should the targeted entities refuse to pay back the ransom.
Other specific victims claimed by the ransomware cartel are reported to be found in Syria, Saudi Arabia, Germany, Spain, Belgium, Turkey, the U.A.E., the U.K., Canada, China, and Taiwan, according to an advisory released by the U.S. Federal Bureau of Investigation (FBI) in March 2022.
Telemetry knowledge collected by Trend Micro exhibits that the foodstuff and beverage sector was the most hit field amongst July 1, 2021 and February 28, 2022, adopted by technology, finance, telecom, and media verticals.
The entry issue for the attack is thought to have been facilitated by leveraging an exploit for a distant code execution flaw in Zoho’s ManageEngine ADSelfService In addition application (CVE-2021-40539) to operate an HTML software (HTA) hosted on a remote server.
“The HTA executed an obfuscated PowerShell script that includes a shellcode, able of connecting again to the [command-and-control] server to execute arbitrary commands,” the researchers stated.
This consists of retrieving an ASPX web shell from the server as perfectly as an installer for the AnyDesk distant desktop software program, the latter of which is used to deploy additional instruments to scan the neighborhood network, terminate security application, and fall the ransomware payload.
Some of the components copied to the contaminated endpoint are a Nmap script to scan the network for the Log4Shell distant code execution flaw (CVE-2021-44228) and a mass deployment device named PDQ to provide a malicious batch script to many endpoints.
The batch script, for its section, is geared up with a wide assortment of abilities that will allow it to disable Windows Update, Windows Defender, and Windows Mistake Restoration, in addition to avoiding safe and sound boot execution of security solutions, building a new admin account, and launching the ransomware binary.
Also utilised is aswArPot.sys, a legitimate Avast anti-rootkit driver, to kill processes linked with diverse security answers by weaponizing a now-fixed vulnerability in the driver the Czech organization settled in June 2021.
“The final decision to pick the certain rootkit driver file is for its ability to execute in kernel method (consequently functioning at a superior privilege),” the researchers pointed out. “This variant is also able of modifying other information of the put in security remedies, these types of as disabling the lawful detect.”
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Some parts of this article are sourced from:
thehackernews.com