SolarWinds releases updated advisory for SUPERNOVA backdoor

SolarWinds released an updated advisory for the SuperNova malware discovered while investigating the recent supply chain attack.

SolarWinds has released an updated advisory for the SuperNova backdoor that was discovered while investigating the recent SolarWinds Orion supply-chain attack.

The SuperNova backdoor was likely used by a separate threat actor.

After the initial disclosure of the SolarWinds attack, several teams of researchers mentioned the existence of two second-stage payloads.

Security experts from Symantec, Palo Alto Networks, and Guidepoint reported that threat actors behind the SolarWinds attack were also planting a .NET web shell dubbed Supernova.

Researchers from Palo Alto Networks revealed that the malicious code is a tainted version of the legitimate .NET library “app_web_logoimagehandler.ashx.b6031896.dll” included in the SolarWinds Orion software.

“In the analysis of the trojanized Orion artifacts, the .NET .dll app_web_logoimagehandler.ashx.b6031896.dll was dubbed SUPERNOVA, but little detail of its operation has been publicly explored.” reads the analysis published by Palo Alto Networks.

“SUPERNOVA differs dramatically in that it takes a valid .NET program as a parameter. The .NET class, method, arguments and code data are compiled and executed in-memory. There are no additional forensic artifacts written to disk, unlike low-level webshell stagers, and there is no need for additional network callbacks other than the initial C2 request. In other words, the SolarStorm attackers have constructed a stealthy and full-fledged .NET API embedded in an Orion binary, whose user is typically highly privileged and positioned with a high degree of visibility within an organization’s network.”

This week, SolarWinds published an updated advisory about the SUPERNOVA backdoor, it includes details about the way it was distributed through the SolarWinds Orion network management platform.

“The SUPERNOVA malware consisted of two components. The first was a malicious, unsigned webshell .dll “app_web_logoimagehandler.ashx.b6031896.dll” specifically written to be used on the SolarWinds Orion Platform. The second is the utilization of a vulnerability in the Orion Platform to enable deployment of the malicious code.” reads the updated advisory. “The vulnerability in the Orion Platform has been resolved in the latest updates.”

SolarWinds urges Orion Platform customers, except those ones already on Orion Platform versions 2019.4 HF 6 or 2020.2.1 HF 2, to apply the latest updates related to the version of the product they have deployed.

The updates include the following versions:

• 2019.4 HF 6 (released December 14, 2020)
• 2020.2.1 HF 2 (released December 15, 2020)
• 2019.2 SUPERNOVA Patch (released December 23, 2020)
• 2018.4 SUPERNOVA Patch (released December 23, 2020)
• 2018.2 SUPERNOVA Patch (released December 23, 2020)

For customers that have already upgraded to the 2020.2.1 HF 2 or 2019.4 HF 6 versions, they cannot be infected with SUNBURST and SUPERNOVA.

SolarWinds provided the following recommendations for the several versions of the SolarWinds Orion Platform:

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Pierluigi Paganini

(SecurityAffairs – hacking, SUPERNOVA)

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