A LockBit ransomware operator or affiliate has been abusing Windows Defender to decrypt and load Cobalt Strike payloads during attacks, according to endpoint security firm SentinelOne.
In April, SentinelOne reported that, in an attack involving LockBit ransomware, threat actors had leveraged a legitimate VMware command-line utility named ‘VMwareXferlogs.exe’ to side-load a Cobalt Strike payload.
In a different attack observed by the cybersecurity firm, the attacker leveraged a command-line tool associated with Windows Defender. Specifically, the hackers used ‘MpCmdRun.exe’ to decrypt and load post-exploitation Cobalt Strike payloads.
The attack started with exploitation of the Log4Shell vulnerability against an instance of VMware Horizon Server. The hackers then conducted reconnaissance and attempted to acquire the privileges needed to download and execute post-exploitation payloads.
“Defenders need to be alert to the fact that LockBit ransomware operators and affiliates are exploring and exploiting novel ‘living off the land’ tools to aid them in loading Cobalt Strike beacons and evading some common EDR and traditional AV detection tools,” SentinelOne said.
“Importantly, tools that should receive careful scrutiny are any that either the organization or the organization’s security software have made exceptions for. Products like VMware and Windows Defender have a high prevalence in the enterprise and a high utility to threat actors if they are allowed to operate outside of the installed security controls,” the company added.
The LockBit ransomware has been around since 2019 and it has likely been used to target thousands of organizations. The cybercriminals encrypt victims’ files and also steal valuable information and threaten to make it public unless a ransom is paid.
LockBit 3.0, aka LockBit Black, emerged recently. More than 60 victims are currently listed on the LockBit 3.0 leak website, with the cybercriminals demanding millions of dollars from some of the victims in order to not make their files public.
LockBit ransomware operators are claiming to offer up to $1 million as part of a bug bounty program for vulnerabilities and various other types of information. However, the cybersecurity community is skeptical of the claims.
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Related: French Ministry of Justice Targeted in Ransomware Attack
Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.
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