Orion

Malicious Domain in SolarWinds Hack Turned into ‘Killswitch’

A key malicious domain name used to control potentially thousands of computer systems compromised via the months-long breach at network monitoring software vendor SolarWinds was commandeered by security experts and used as a “killswitch” designed to turn the sprawling cybercrime operation against itself, KrebsOnSecurity has learned.

Austin, Texas-based SolarWinds disclosed this week that a compromise of its software update servers earlier this year may have resulted in malicious code being pushed to nearly 18,000 customers of its Orion platform. Many U.S. federal agencies and Fortune 500 firms use(d) Orion to monitor the health of their IT networks.

On Dec. 13, cyber incident response firm FireEye published a detailed writeup on the malware infrastructure used in the SolarWinds compromise, presenting evidence that the Orion software was first compromised back in March 2020. FireEye said hacked networks were seen communicating with a malicious domain name — avsvmcloud[.]com — one of several domains the attackers had set up to control affected systems.

As first reported here on Tuesday, there were signs over the past few days that control over the domain had been transferred to Microsoft. Asked about the changeover, Microsoft referred questions to FireEye and to GoDaddy, the current domain name registrar for the malicious site.

Today, FireEye responded that the domain seizure was part of a collaborative effort to prevent networks that may have been affected by the compromised SolarWinds software update from communicating with the attackers. What’s more, the company said the domain was reconfigured to act as a “killswitch” that would prevent the malware from continuing to operate in some circumstances.

“SUNBURST is the malware that was distributed through SolarWinds software,” FireEye said in a statement shared with KrebsOnSecurity. “As part of FireEye’s analysis of SUNBURST, we identified a killswitch that would prevent SUNBURST from continuing to operate.”

The statement continues:

“Depending on the IP address returned when the malware resolves avsvmcloud[.]com, under certain conditions, the malware would terminate itself and prevent further execution. FireEye collaborated with GoDaddy and Microsoft to deactivate SUNBURST infections.”

“This killswitch will affect new and previous SUNBURST infections by disabling SUNBURST deployments that are still beaconing to avsvmcloud[.]com. However, in the intrusions FireEye has seen, this actor moved quickly to establish additional persistent mechanisms to access to victim networks beyond the SUNBURST backdoor.

This killswitch will not remove the actor from victim networks where they have established other backdoors. However, it will make it more difficult to for the actor to leverage the previously distributed versions of SUNBURST.”

It is likely that given their visibility into and control over the malicious domain, Microsoft, FireEye, GoDaddy and others now have a decent idea which companies may still be struggling with SUNBURST infections.

The killswitch revelations came as security researchers said they’d made progress in decoding SUNBURST’s obfuscated communications methods. Chinese cybersecurity firm RedDrip Team published their findings on Github, saying its decoder tool had identified nearly a hundred suspected victims of the SolarWinds/Orion breach, including universities, governments and high tech companies.

Meanwhile, the potential legal fallout for SolarWinds in the wake of this breach continues to worsen. The Washington Post reported Tuesday that top investors in SolarWinds sold millions of dollars in stock in the days before the intrusion was revealed. SolarWinds’s stock price has fallen more than 20 percent in the past few days. The Post cited former enforcement officials at the U.S. Securities and Exchange Commission (SEC) saying the sales were likely to prompt an insider trading investigation.

U.S. Treasury, Commerce Depts. Hacked Through SolarWinds Compromise

Communications at the U.S. Treasury and Commerce Departments were reportedly compromised by a supply chain attack on SolarWinds, a security vendor that helps the federal government and a range of Fortune 500 companies monitor the health of their IT networks. Given the breadth of the company’s customer base, experts say the incident may be just the first of many such disclosures.

Some of SolarWinds’ customers. Source: solarwinds.com

According to a Reuters story, hackers believed to be working for Russia have been monitoring internal email traffic at the U.S. Treasury and Commerce departments. Reuters reports the attackers were able to surreptitiously tamper with updates released by SolarWinds for its Orion platform, a suite of network management tools.

In a security advisory, Austin, Texas based SolarWinds acknowledged its systems “experienced a highly sophisticated, manual supply chain attack on SolarWinds Orion Platform software builds for versions 2019.4 HF 5 through 2020.2.1, released between March 2020 and June 2020.”

In response to the intrusions at Treasury and Commerce, the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency (CISA) took the unusual step of issuing an emergency directive ordering all federal agencies to immediately disconnect the affected Orion products from their networks.

“Treat all hosts monitored by the SolarWinds Orion monitoring software as compromised by threat actors and assume that further persistence mechanisms have been deployed,” CISA advised.

A blog post by Microsoft says the attackers were able to add malicious code to software updates provided by SolarWinds for Orion users. “This results in the attacker gaining a foothold in the network, which the attacker can use to gain elevated credentials,” Microsoft wrote.

From there, the attackers would be able to forge single sign-on tokens that impersonate any of the organization’s existing users and accounts, including highly privileged accounts on the network.

“Using highly privileged accounts acquired through the technique above or other means, attackers may add their own credentials to existing application service principals, enabling them to call APIs with the permission assigned to that application,” Microsoft explained.

Malicious code added to an Orion software update may have gone undetected by antivirus software and other security tools on host systems thanks in part to guidance from SolarWinds itself. In this support advisory, SolarWinds says its products may not work properly unless their file directories are exempted from antivirus scans and group policy object restrictions.

The Reuters story quotes several anonymous sources saying the intrusions at the Commerce and Treasury departments could be just the tip of the iceberg. That seems like a fair bet.

SolarWinds says it has over 300,000 customers including:

-more than 425 of the U.S. Fortune 500
-all ten of the top ten US telecommunications companies
-all five branches of the U.S. military
-all five of the top five U.S. accounting firms
-the Pentagon
-the State Department
-the National Security Agency
-the Department of Justice
-The White House.

It’s unclear how many of the customers listed on SolarWinds’ website are users of the affected Orion products. But Reuters reports the supply chain attack on SolarWinds is connected to a broad campaign that also involved the recently disclosed hack at FireEye, wherein hackers gained access to a slew of proprietary tools the company uses to help customers find security weaknesses in their computers and networks.

The compromises at the U.S. federal agencies are thought to date back to earlier this summer, and are being blamed on hackers working for the Russian government.

In its own advisory, FireEye said multiple updates poisoned with a malicious backdoor program were digitally signed with a SolarWinds certificate from March through May 2020, and posted to the SolarWindws update website.

FireEye posits the impact of the hack on SolarWinds is widespread, affecting public and private organizations around the world.

“The victims have included government, consulting, technology, telecom and extractive entities in North America, Europe, Asia and the Middle East,” the company’s analysts wrote. “We anticipate there are additional victims in other countries and verticals.”

Update, 8:30 p.m. ET: An earlier version of this story incorrectly stated that FireEye attributed the SolarWinds attack to APT29. That information has been removed from the story.