Government organisations in India, Brazil, Kazakhstan, Russia, Thailand and Turkey suffered damage as a result of the group's attacks, said specialists from London-headquartered global security solutions provider Positive Technologies.
The Calypso APT (or Advanced Persistent Threat) group has been active since 2016, Engadget reported on Monday.
To get access to the victim's internal network, the attackers hack the network perimeter and inject a special programme which gave them, the investigation by Positive Technologies found.
The investigation revealed that the attackers moved along the network either by exploiting Remote Code Execution vulnerability (MS17-010) or by using stolen credentials.
"These attacks succeeded largely because most of the utilities the group uses to move inside the network are widely used by the specialists everywhere for network administration," Denis Kuvshinov, Lead Specialist in Threat Analysis at Positive Technologies said in a statement.
"The group used publicly available utilities and exploit tools, such as SysInternals, Mimikatz; EternalBlue, and EternalRomance. Using these widely available tools, the attackers infected computers on the organisation's LAN ( local area network) and stole confidential data," Kuvshinov said.
According to the experts at Positive Technologies, organisations can prevent such attacks by using specialised systems for deep traffic analysis.
These systems facilitate the detection of suspicious activity at the early stages of the attackers' incursion into the LAN, and then would prevent the hackers from getting a foothold in the company infrastructure.
In addition, monitoring of security incidents, along with perimeter and web applications protection, can also help in detecting and preventing these attacks.
In one of the attacks the group used PlugX malware - traditionally used by many Chinese APT groups. They also used Byeby trojan, which was involved in the SongXY malware campaign in 2017.
Also, in some of the attacks the hackers accidentally disclosed their real IP addresses, which belonged to Chinese providers.
"The group has several successful hacks to its credit, but still makes mistakes allowing us to guess its origins," Positive Technologies said in a report.
"We keep monitoring the activities of Calypso closely and expect the group will attack again," it added.
( With inputs from IANS )