The malware has not been given a name yet, but Kaspersky says it is similar to Duqu 2.0 that attacked its own network and stayed undetected for more than six months.

It said an unnamed bank found the malware in late 2016 after it detected Meterpreter code in the physical memory of one of its Windows domain controllers. Meterpreter is an advanced, dynamically extensible payload that uses in-memory DLL injection stagers and is extended over the network at runtime.

Participating in the analysis of the malware, Kasperksy says it found the use of PowerShell scripts within the Windows registry. Additionally, the Windows NETSH utility was used to tunnel traffic from the host to the attacker's command and control centre. Another standard Windows utility, SC, was also used.

Since SC and NETSH can only be used by administrators on a Windows system, the malware used credentials from accounts which have administrative privileges. These were obtained using the post-exploitation tool Mimikatz, which is part of the Metasploit framework.

Graphic courtesy Kaspersky.

Kaspersky then used its own security network to check on the prevalence of the malware and claimed that more than 100 business networks were infected with PowerShell scripts in the registry.

"During our analysis of the affected bank we learned that the attackers had used several third level domains and domains in the .GA, .ML, .CF ccTLDs. The trick of using such domains is that they are free and missing WHOIS information after domain expiration," the company said.

Since the attackers were using the Metasploit framework, standard Windows utilities and domains that had no WHOIS information, Kaspersky said it was not possible to ascertain who was behind the attacks.

Kaspersky's description includes ways to spot if a system if infected.