Attackers Infiltrate a Single Server for Five Months, Using it to Browse Online for Tools to Help Them With Further Parts of the Attack, Sophos Finds

Sophos Press Release

Attackers also Deploy a Cryptominer and Lockbit Ransomware

OXFORD, U.K. – April 12, 2022 – Sophos, a global leader in next-generation cybersecurity, today released findings on how attackers breached and spent five months inside a regional government server in the U.S., using it to browse online for a mix of hacker and IT administration tools that could help them carry out the attack. The attackers also installed a cryptominer before exfiltrating data and deploying Lockbit ransomware. The findings are detailed in a new article, “Attackers Linger on Government Agency Computers Before Deploying Lockbit Ransomware,” and suggest that multiple attackers infiltrated the vulnerable server. The attack was contained and investigated by Sophos’ incident response team.

“This was a very messy attack. Working together with the target, Sophos researchers were able to build a picture that started with what appears to be novice attackers breaking into the server, poking around the network and using the compromised server to Google a combination of pirated and free versions of hacker and legitimate admin tools to use in their attack. They then seemed unsure of what to do next,” said Andrew Brandt, principal security researcher at Sophos. “About four months after the initial breach, the nature of the attack activity changed, in some cases so drastically that it suggests attackers with very different skills had joined the fray. These attackers went on to attempt to uninstall security software. They eventually stole data and encrypted files on several machines by deploying Lockbit ransomware.”

The Sequence of Attack

Sophos researchers found that the initial point of access for the attack was an open remote desktop protocol (RDP) port on a firewall that was configured to provide public access to a server. The attackers breached the server in September 2021. They then used a browser on the breached server to search online for the tools to use for hacking and attempted to install them. In some cases, the search for tools led the attackers to shady download sites that delivered adware to the hacked server, instead of the tools they were looking for.

The research shows that attackers’ behaviors changed significantly in mid-January, with signs of more skilled and focused activity. These attackers attempted to remove the malicious cryptominer and uninstall security software, taking advantage of the fact that the target had inadvertently left a protective feature disabled after completing maintenance. The attackers then collected and exfiltrated data and deployed the Lockbit ransomware. The ransomware attack had limited success and the attackers failed to encrypt data on some machines.

Staying Protected

The tools the attackers tried to install for malicious purposes included Advanced Port Scanner, FileZilla, LaZagne, mimikatz, NLBrute, Process Hacker, PuTTY, Remote Desktop Passview, RDP Brute Forcer, SniffPass, and WinSCP. The attackers also installed commercial remote access tools, including ScreenConnect and AnyDesk.

“If a member of the IT team hasn’t downloaded them for a specific purpose, the presence of such tools on machines on your network is a red flag for an ongoing or imminent attack,” said Brandt. “Unexpected or unusual network activity, such as a machine scanning the network is another such indicator. Repeated RDP login failures on a machine only accessible inside the network is a sign someone might be using a brute-force tool to try to move laterally. As are active connections from commercial remote access tools the IT team has not installed or may have used in the past but have not used for a while.

“A robust, proactive, 24/7 defense-in-depth approach will help to prevent such an attack from taking hold and unfolding. The most important first step is to try to prevent attackers from gaining access to a network in the first place, for example by implementing multi-factor authentication and setting firewall rules to block remote access to RDP ports in the absence of a VPN connection.”

For further information read the article, “Attackers Linger on Government Agency Computers Before Deploying Lockbit Ransomware” on Sophos News.

About Sophos

Sophos is a worldwide leader and innovator of advanced cybersecurity solutions, including Managed Detection and Response (MDR) and incident response services and a broad portfolio of endpoint, network, email, and cloud security technologies that help organizations defeat cyberattacks. As one of the largest pure-play cybersecurity providers, Sophos defends more than 500,000 organizations and more than 100 million users globally from active adversaries, ransomware, phishing, malware, and more. Sophos’ services and products connect through its cloud-based Sophos Central management console and are powered by Sophos X-Ops, the company’s cross-domain threat intelligence unit. Sophos X-Ops intelligence optimizes the entire Sophos Adaptive Cybersecurity Ecosystem, which includes a centralized data lake that leverages a rich set of open APIs available to customers, partners, developers, and other cybersecurity and information technology vendors. Sophos provides cybersecurity-as-a-service to organizations needing fully-managed, turnkey security solutions. Customers can also manage their cybersecurity directly with Sophos’ security operations platform or use a hybrid approach by supplementing their in-house teams with Sophos’ services, including threat hunting and remediation. Sophos sells through reseller partners and managed service providers (MSPs) worldwide. Sophos is headquartered in Oxford, U.K. More information is available at www.sophos.com.