Sunspot

Sunspot is an implant that injected the Sunburst backdoor into the SolarWinds Orion software update framework. It was used by UNC2452 since at least February 2020.[1]

ID: S0562
Type: MALWARE
Platforms: Windows
Version: 1.0
Created: 12 January 2021
Last Modified: 22 January 2021

Techniques Used

Domain ID Name Use
Enterprise T1134 Access Token Manipulation

Sunspot modified its security token to grants itself debugging privileges by adding SeDebugPrivilege.[1]

Enterprise T1565 .001 Data Manipulation: Stored Data Manipulation

Sunspot created a copy of the SolarWinds Orion software source file with a .bk extension to backup the original content, wrote Sunburst using the same filename but with a .tmp extension, and then moved Sunburst using MoveFileEx to the original filename with a .cs extension so it could be compiled within Orion software.[1]

Enterprise T1140 Deobfuscate/Decode Files or Information

Sunspot decrypts Sunburst, which was stored in AES128-CBC encrypted blobs.[1]

Enterprise T1480 Execution Guardrails

Sunspot only replaces SolarWinds Orion source code if the MD5 checksums of both the original source code file and backdoored replacement source code match hardcoded values.[1]

Enterprise T1083 File and Directory Discovery

Sunspot enumerated the Orion software Visual Studio solution directory path.[1]

Enterprise T1070 .004 Indicator Removal on Host: File Deletion

Following the successful injection of Sunburst, Sunspot deleted a temporary file it created named InventoryManager.bk after restoring the original SolarWinds Orion source code to the software library.[1]

Enterprise T1036 .005 Masquerading: Match Legitimate Name or Location

Sunspot was identified on disk with a filename of taskhostsvc.exe and it created an encrypted log file at C:\Windows\Temp\vmware-vmdmp.log.[1]

Enterprise T1106 Native API

Sunspot used Windows API functions such as MoveFileEx and NtQueryInformationProcess as part of the Sunburst injection process.[1]

Enterprise T1027 Obfuscated Files or Information

Sunspot encrypted log entries it collected with the stream cipher RC4 using a hard-coded key. It also uses AES128-CBC encrypted blobs for Sunburst source code and data extracted from the SolarWinds Orion process.[1]

Enterprise T1057 Process Discovery

Sunspot monitored running processes for instances of MsBuild.exe by hashing the name of each running process and comparing it to the corresponding value 0x53D525. It also extracted command-line arguments and individual arguments from the running MsBuild.exe process to identify the directory path of the Orion software Visual Studio solution.[1]

Enterprise T1195 .002 Supply Chain Compromise: Compromise Software Supply Chain

Sunspot malware was designed and used to insert Sunburst into software builds of the SolarWinds Orion IT management product.[1]

Groups That Use This Software

ID Name References
G0118 UNC2452

[1]

References