Microsoft today announced that Microsoft Defender will begin quarantining compromised SolarWind Orion binaries starting tomorrow morning.
Over the weekend, it was revealed that Russian nation-state hackers had compromised SolarWinds, a developer of network management software, and added malicious code to their Orion platform.
The malicious binaries were then distributed through SolarWinds’ automatic update mechanism to approximately 18,000 customers, including numerous US government agencies. The threat actors used these malicious binaries to install a backdoor known as Solorigate (Microsoft) or SUNBURST (FireEye).
Although Microsoft is already detecting and quarantining the backdoor, they have not quarantined the compromised SolarWinds binaries as it could affect critical network management activities used by customers.
Due to the threat of this trojanized software, Microsoft announced that Microsoft Defender will quarantine compromised SolarWinds binaries starting tomorrow, December 16 at 8:00 am PST.
“It is important to understand that these binaries pose a significant threat to customer environments. Customers should consider any device with the binary as compromised and should investigate devices with this warning as early as Wednesday December 16 at 8:00 am PST, Microsoft Defender Antivirus starts by blocking the known malicious SolarWinds binaries, which will quarantine the binary even while the process is running, “Microsoft announced today.
Microsoft Defender detects compromised SolarWinds binaries as’Trojan: MSIL / Solorigate.BR! Dha. ‘
Microsoft also recommends isolating all servers running SolarWinds software from the rest of the environment and thoroughly examining them for malicious software before returning them to service.
The following steps are suggested:
- Immediately isolate the affected device. If malicious code has been launched, it is likely that the device is under full control of the attacker.
- Identify the accounts used on the affected device and consider those accounts as compromised. Reset passwords or take the accounts out of business.
- Investigate how the affected endpoint may have been affected.
- Examine the device’s timeline for indications of lateral movement activity using one of the compromised accounts. Check for additional tools that attackers may have dropped to enable access to credentials, sideways movement and other attack activities.
If service interruption is not possible, Microsoft has created a GPO policy that can be used to change the behavior of Microsoft Defender so that it does not remove detected compromised SolarWinds binaries.