Threat Advisory: SolarWinds supply chain attack

I have been receiving numerous asks about the recent SolarWinds attack. Yesterday, CISA issued an advisory here that, among other things, said that the SolarWinds Orion supply chain compromise is not the only initial infection vector this APT actor leveraged. This obviously stirs up more questions than answers and has driven quite a news cycle of speculation.

Cisco Talos posted about this and continues to keep details up to date found here. Below is that message from Talos. Keep checking back to the Talos post as they gather more information about the situation.

Update 12/17: Additional IOCs added related to teardrop secondary payload.

Update 12/16: Based on the announcement from FireEye, Microsoft, and GoDaddy avsvmcloud[.]com has been unblocked as it is now functioning as a kill switch in an effort to help limit adversaries access. Please note that this does not imply that this is a complete protection from these attacks. Additional remediation steps will should and must be taken. Additional details here.

Update 12/14: We note there is a discrepancy in guidance coming from DHS and SolarWinds. The SolarWinds advisory suggests users upgrade to the latest version, Orion Platform version 2020.2.1 HF 1, while DHS guidance says 2020.2.1 HF1 is affected. However, we note that SolarWinds announced they will be releasing another hot-fix, 2020.2.1 HF 2, on December 15, which “replaces the compromised component and provides several additional security enhancements.” Talos urges customers to follow DHS guidance at this time and install 2020.2.1 HF 2 as soon as it becomes available.Cisco Talos is monitoring yesterday’s announcements by FireEye and Microsoft that a likely state-sponsored actor compromised potentially thousands of high-value government and private organizations around the world via the SolarWinds Orion product. FireEye reported on Dec. 8 that it had been compromised in a sophisticated attack in which state-sponsored actors stole sensitive red team tools. Upon investigating the breach further, FireEye and Microsoft discovered that the adversary gained access to victims’ networks via trojanized updates to SolarWinds’ Orion software.

Threat activity details

In another sophisticated supply-chain attack, adversaries compromised updates to the SolarWinds Orion IT monitoring and management software, specifically a component called “SolarWinds.Orion.Core.BusinessLayer.dll” in versions 2019.4 HF 5 through 2020.2.1. The digitally signed updates were posted on the SolarWinds website from March to May 2020. This backdoor is being tracked by FireEye as SUNBURST, and it can communicate to third-party servers using HTTP. The backdoor is loaded by the actual SolarWinds executable before the legitimate code, as not to alert the victim that anything is amiss.

After a period of dormancy, which can last up to two weeks, the backdoor can execute commands to transfer and execute files, profile the system, reboot the machine and disable system services. Note that a number of SUNBURST samples have been observed along with varying payloads, including a memory-only dropper dubbed “Teardrop,” which was then used to deploy Cobalt Strike beacons.

The adversaries leverage administrative privileges obtained during the on-premise compromise to access the victim’s global administrator account and/or trusted SAML token-signing certificate. The adversary can forge SAML tokens that impersonate any of the organization’s existing users and accounts, including highly privileged accounts, allowing them to bypass multi-factor authentication for services such as Office365 suite. Security researchers have observed that the targeted users are often key IT and security personnel. Because the SAML tokens are signed with their own trusted certificate, they can be used to log in to any on-premise resource or cloud environment, regardless of vendor.

The adversary also uses sophisticated techniques for communications. The backdoor identifies its command and control (C2) server using a domain-generated algorithm (DGA) to construct and resolve a subdomain of avsvmcloud[.]com, which it can use to deliver second-stage payloads and access or exfiltrate data. Network traffic originating from the malware appears as legitimate Orion protocol traffic and the adversaries store information in legitimate plugin configuration files, all causing it to look like normal SolarWind network traffic. The actor sets the hostnames on their C2 infrastructure to match legitimate hostnames found within the victim’s environment. The adversary mainly relied on IP addresses originating from the same country as the victim — all of which are designed to evade detection.

Initial findings suggest that the campaign began in March 2020 and lasted several months. SolarWinds and CISA issued security advisories warning of active exploitation of the SolarWinds Orion Platform software released between March and June, and Microsoft has been tracking the SUNBURST backdoor since March.


SolarWinds confirmed that less than 18,000 of its 300,000 customers have downloaded the compromised update. Still, the effects of this campaign are potentially staggering, with the company’s products being used by several high-value entities. Victims reportedly include government agencies and consulting, technology, telecom, and oil and gas companies in North America, Europe, Asia and the Middle East, according to FireEye. Several reports also indicate that the U.S. Treasury and Commerce departments were also targeted in what is likely related to the same activity.


SolarWinds issued a security advisory recommending users upgrade to the latest version, Orion Platform version 2020.2.1 HF 1, as soon as possible. In response to this activity, on Dec. 13, 2020 the U.S. Department of Homeland Security (DHS) and CISA issued an emergency alert calling on all U.S. federal civilian agencies to review their networks for indicators of compromise (IOCs) and advising them to disconnect SolarWinds Orion products immediately. Microsoft has named this attack “Solorigate” in Windows Defender and, along with other industry partners, has published guidance and timelines for this activity.

CISA and DHS provided required actions and mitigations in their advisories:

  • Reimage system memory and/or host operating systems hosting all instances of SolarWinds Orion versions 2019.4 through 2020.2.1 HF1, and analyze for new user or service accounts.
  • Disconnect or power down SolarWinds Orion products, versions 2019.4 through 2020.2.1 HF1, from their network.
  • Identify the existence of “SolarWinds.Orion.Core.BusinessLayer.dll” and “C:\WINDOWS\SysWOW64\netsetupsvc.dll”.
  • Block all traffic to and from hosts where any version of SolarWinds Orion software has been installed.
  • Identify and remove threat-actor controlled accounts and persistence mechanisms.
  • Reset all credentials used by SolarWinds software and implement a rotation policy for these accounts. Require long and complex passwords.
  • See Microsoft’s guidance and documentation on kerberoasting.

We urge all organizations that use the SolarWinds Orion IT monitoring and management software to carefully follow the guidance from DHS and CISA. We also note that Cobalt Strike was observed being leveraged in these attacks. Cisco Talos released a research paper detailing the large amount of coverage for the Cobalt Strike framework. Our pre-existing coverage is still applicable and can reliably detect FireEye red team beacons and other activity.

Incident Response

Cisco Talos Incident Response (CTIR) is currently supporting retainer customers in regard to the SolarWinds Orion Sunburst backdoor. CTIR recommends organizations update incident response plans, playbooks, or a tabletop exercise (TTX) to test the organization’s ability to respond to a supply-chain attack. Finally, once mitigation efforts have been successfully put in place, CTIR recommends a targeted threat hunt leveraging indicators and adversary TTPs.


Ways our customers can detect and block this threat are listed below.

  • SIDs 56660-56668

Advanced Malware Protection (AMP) is ideally suited to prevent the execution of the malware detailed in this post. Below is a screenshot showing how AMP can protect customers from this threat. Try AMP for free here. Cisco Cloud Web Security (CWS) or Web Security Appliance (WSA) web scanning prevents access to malicious websites and detects malware used in these attacks. Email Security can block malicious emails sent by threat actors as part of their campaign. Network Security appliances such as Next-Generation Firewall (NGFW), Next-Generation Intrusion Prevention System (NGIPS), Cisco ISR, and Meraki MX can detect malicious activity associated with this threat. Threat Grid helps identify malicious binaries and build protection into all Cisco Security products. Umbrella, our secure internet gateway (SIG), blocks users from connecting to malicious domains, IPs, and URLs, whether users are on or off the corporate network. Additional protections with context to your specific environment and threat data are available from the Firepower Management Center. Open Source Snort Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Cisco customers that are concerned about potential impacts to Cisco products, please see the PSIRT advisory available here.

Indicators of compromise (IOCs)

avsvmcloud[.]comzupertech[.]companhardware[.]comdatabasegalore[.]comincomeupdate[.]comhighdatabase[.]comwebsitetheme[.]comfreescanonline[.]comvirtualdataserver[.]comdeftsecurity[.]comthedoccloud[.]comdigitalcollege[.]orgglobalnetworkissues[.]comseobundlekit[.]comvirtualwebdata[.]comervsystem[.]com (teardrop)infinitysoftwares[.]com (teardrop)
Hashes (SHA256):

1817a5bf9c01035bcf8a975c9f1d94b0ce7f6a200339485d8f93859f8f6d730c (teardrop)b820e8a2057112d0ed73bd7995201dbed79a79e13c79d4bdad81a22f12387e07 (teardrop)

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