Pierluigi Paganini January 11, 2022

Another gang, Night Sky ransomware operation, started exploiting the Log4Shell vulnerability in the Log4j library to gain access to VMware Horizon systems.

The Night Sky ransomware operation started exploiting the Log4Shell flaw (CVE-2021-44228) in the Log4j library to gain access to VMware Horizon systems.

The ransomware gang started its operations on December 27, 2021, and has already hacked the corporate networks of two organizations from Bangladesh and Japan respectively. The gang has also set up a leak site on the Tor network where it will publish files stolen to the victims that will not pay the ransom.

Researchers from MalwareHunterteam first spotted the ransomware family, once encrypted a file, the ransomware appends the ‘.nightsky‘ extension to encrypted file names.

In early January, threat actors started targeting VMware Horizon systems exposed on the Internet. VMware has addressed Log4Shell in Horizon with the release of 2111, 7.13.1, 7.10.3 versions, but unfortunately many unpatched systems are still exposed online.

On Monday, Microsoft posted a warning about a new campaign from a China-based actor it tracks as DEV-0401 to exploit the Log4Shell vulnerability on VMware Horizon systems exposed on the internet, and deploy Night Sky ransomware.

According to Microsoft the ransomware operators compromised the exposed systems to deploy the NightSky ransomware. The DEV-0401 operators have also deployed multiple ransomware families in past campaigns, including LockFile, AtomSilo.

“As early as January 4, attackers started exploiting the CVE-2021-44228 vulnerability in internet-facing systems running VMware Horizon. Our investigation shows that successful intrusions in these campaigns led to the deployment of the NightSky ransomware.” reads an update published by Microsoft.

“These attacks are performed by a China-based ransomware operator that we’re tracking as DEV-0401. DEV-0401 has previously deployed multiple ransomware families including LockFile, AtomSilo, and Rook, and has similarly exploited Internet-facing systems running Confluence (CVE-2021-26084) and on-premises Exchange servers (CVE-2021-34473).

According to Microsoft Night Sky ransomware operators employed C2 servers that impersonate domains used by legitimate companies such as cybersecurity firms Trend Micro, Sophos, and IT firms such as Nvidia and Rogers Corporation.

In the last weeks other ransomware gangs exploited the Log4Shell in their attacks, the Conti ransomware gang was the first group that exploited the CVE-2021-44228 flaw since mid December.

In the same period, Bitdefender researchers discovered that threat actors were attempting to exploit the Log4Shell vulnerability to deliver the new Khonsari ransomware on Windows machines

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Pierluigi Paganini

(SecurityAffairs – hacking, Log4Shell)

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