Wednesday, April 17, 2024

Lemon Duck Group Attacks Microsoft Exchange Servers


Researchers have analyzed the most recent activities of the Lemon Duck team of cybercriminals, including their exploitation of Microsoft Trade Server vulnerabilities and the use of bogus major-degree domains.

Exploitation of Microsoft Exchange Server vulnerabilities by cybercriminals has been a stability disaster for hundreds of businesses.

Four important vulnerabilities, named ProxyLogon, affected on-premises Microsoft Exchange 2013, 2016, and 2010 servers. Patches, vulnerability detection instruments, and mitigation suggestions were made accessible in March, but up to 60,000 corporations are still estimated. they could have been compromised. The exploit code is now offered as properly, and at minimum 10 sophisticated cybercriminal groups have embraced the loopholes in their assaults this 12 months.

The Lemon Duck botnet beneath the microscope

In late March, Microsoft warned that the Lemon Duck botnet was making an attempt to exploit vulnerable servers and use compromised devices to mine cryptocurrencies. Nowadays, Cisco Talos scientists have posted an in-depth investigation tactics of this group.

Lemon Duck operators are integrating new instruments to “maximize the performance of their campaigns” by concentrating on vulnerabilities in Microsoft Exchange Server. Telemetry info from DNS queries to Lemon Duck domains implies that marketing campaign activity peaked in April. Most of the requests came from the United States, followed by Europe and Southeast Asia. There was also a major maximize in requests for a Lemon Duck domain in India.

Lemon Duck operators use automated resources to examine, detect, and exploit servers right before setting up payloads, this sort of as Cobalt Strike DNS tags and internet shells, permitting them to operate mining software, additional cryptocurrencies, and malware.

Get rid of antivirus

The malware and connected PowerShell scripts will also endeavor to take out antivirus merchandise provided by sellers such as ESET and Kaspersky and shut down any providers, which include Windows Update and Windows Defender, that could hamper an an infection try.

Scheduled responsibilities are made to maintain persistence, and in the latest strategies the CertUtil command line system is used to download two new PowerShell scripts liable for eliminating antivirus merchandise, producing persistence routines, and downloading a variant of the XMRig cryptocurrency miner .

The signatures of competing cryptocurrency miners are also listed in a “killer” module meant to remove them.

SMBGhost and Eternal Blue have been applied in earlier campaigns, but as exploiting Microsoft Exchange Server flaws shows, the group’s ways are frequently modifying to continue to be forward.

Fictional domains

Lemon Duck also designed fictitious top rated-degree domains (TLDs) for China, Japan, and South Korea, in an try to disguise the infrastructure of the Command and Management (C2) centers.

“Considering that these ccTLDs are employed additional commonly for internet websites in their respective nations and languages, it is also fascinating that they have been utilised in relationship with this assault, fairly than additional generic and entire world-broad TLDs like” .com ” or “.net”, “suggests Cisco Talos. “This can enable the destructive actor to much more properly hide communications to the regulate server from other web site visitors present in the victim’s environments. “

One-way links have also been observed between the Lemon Duck botnet and the Beapy / Pcastle cryptocurrency malware.

“The use of new tools, such as Cobalt Strike, as properly as the implementation of additional obfuscation techniques in the course of the assault everyday living cycle, can let them to function more effectively for more time intervals of time in the attack, inside the ecosystem. of the victims, ”he claims. researchers. “The new methods and extra host-primarily based evidence suggest that this participant is now also displaying a particular curiosity in Trade servers as he makes an attempt to compromise extra systems and maintain and / or improve the quantity of devices within the Lemon Duck botnet. . “

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Mortimer Rodgers
Mortimer Rodgers
Professional bacon fanatic. Explorer. Avid pop culture expert. Introvert. Amateur web evangelist.

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