Volt Typhoon, a China-government backed hacking group that has infiltrated America’s critical infrastructure networks for years, has consistently built and dismantled ephemeral malicious infrastructure to burrow into hundreds of sensitive systems undetected, Lumen Technologies’ Black Lotus Labs said in a Wednesday report.

The covert access operation that researchers call “Silent Train” isn’t a standalone network, but rather a series of compromised small office home office (SOHO) routers, internet of things (IoT) devices and enterprise infrastructure that Volt Typhoon has rapidly rotated through since late 2023. 

The Chinese threat group has used this chain of short-lived compromised infrastructure to exploit additional vulnerabilities, including zero-days, in network edge devices and gain deeper, persistent access into victim networks, researchers said. 

“Individual chains are assembled and dismantled every day, with infrastructure continually refreshed,” Michael Horka, principal information security engineer at Black Lotus Labs, told CyberScoop. “Volt Typhoon demonstrated a repeatable capability to rebuild a new chain with different infrastructure in less than two minutes, making the number of nodes at any one moment effectively close to zero.”

Black Lotus Labs has notified hundreds of victims since it first identified Silent Train activity, including telecom providers, government entities, defense contractors, communication services, universities and IT firms. Other victims spanning critical infrastructure include organizations in the water, energy, transportation, maritime, rail, aviation and emergency services sectors.

“The ephemeral nature of the framework means our observations should not be interpreted as a complete census of Volt Typhoon activity,” said Horka, who also was the lead researcher on the report.

The nation-state group’s investment in operational security and preserving access is remarkable, according to Black Lotus Labs.

“We observed infrastructure assembled in under two minutes, sessions averaging roughly four hours, extensive cleanup, compartmentalization and continued development of new access vectors,” Horka said. “That is considerable effort devoted not even to get into their end targets, but purely to making important operations difficult to discover and trace.”

Volt Typhoon relied more heavily on Silent Train after the FBI and Justice Department disrupted the KV Botnet in early 2024, researchers said. Earlier this year, U.S. and global authorities warned about a widespread shift in Chinese hacking groups’ use of covert networks riding on compromised common devices.

The reach of those efforts is extensive and ongoing. Volt Typhoon has exploited and abused more than 27 device classes in Silent Train operations, including edge devices, enterprise management tools, identity and access management systems, networking infrastructure and other technologies. 

“The diversity matters, but the discipline matters even more,” Horka said. “Specific device types were consistently reserved for particular positions in the chain. It operated less like a collection of randomly compromised devices and more like an organized inventory of capabilities.”

The threat group has successfully compromised devices and technologies from Fortinet, Cisco, ManageEngine, Ivanti, F5, Check Point, Palo Alto Networks, ServiceNow, TP-Link, Netgear and ArcGIS, researchers said. Black Lotus Labs also observed confirmed zero-day campaigns targeting Versa Director, N-Able N-Central, Cisco Catalyst SD-WAN and VeloCloud Orchestrator. 

“The exploitation patterns, victimology, and geographic targeting observed throughout our investigation point to a sustained focus on communications, defense, government, and critical infrastructure environments of enduring strategic value,” Black Lotus Labs researchers wrote in the report. “Through repeated targeting of centralized management platforms and control-plane technologies, Silent Train shows how Volt Typhoon systematically pursues and preserves access to some of the most consequential networks in the United States.”

Silent Train’s ephemerality and operational discipline means it can’t be measured in size. These attributes also make it “fundamentally difficult to disrupt because there isn’t one network to take down,” Horka said. 

“What exists today will be completely different tomorrow,” he added. “You can try to remove individual pieces, but removing the actor’s ability to continuously rebuild them is a much harder problem to solve.”

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Suspected Chinese hackers with a proven knack for exploiting zero-days in security products are at it again, targeting BeyondTrust customers in attacks that researchers have traced back to late August. 

Mandiant researchers said a likely Chinese government-backed espionage group it previously tracked as UNC5221, and now calls Armory Castle, exploited the critical defect — CVE-2026-102764 — then showcased multiple tactics to escalate privileges, hop around the compromised network and evade detection. 

The same threat group has repeatedly exploited a series of defects in Ivanti products since 2023, a Citrix NetScaler zero-day widely known as CitrixBleed, and last year’s Brickstorm campaign that had an average dwell time of 400 days — all resulting in sweeping attack sprees.

“We are aware of only a small number of impacted organizations at this time, but given the stealth of the activity, and the use of a zero-day, it is possible that additional organizations were also compromised prior to the disclosure,” Kelli Vanderlee, senior analyst at Google Threat Intelligence Group, said in an email.

Mandiant warned organizations to “prepare for potential widespread exploitation,” adding that Armory Castle and other threat groups previously conducted broad, opportunistic exploitation following public vulnerability disclosures.

Mandiant and GTIG released their analysis of Armory Castle and its latest campaign as BeyondTrust publicly disclosed the vulnerability in its Remote Support product Thursday. The company’s security said it released a patch for the exploited defect for self-hosted customers Oct. 8 and automatically applied the update to cloud-based versions of the product that same day.

BeyondTrust, which conducted its own investigation and coordinated with Mandiant on an investigation involving a self-hosted customer that was compromised, noted Armory Castle’s prowess.

“This threat actor rotates its infrastructure and tooling for every victim, so attribution here rests on behavior. The indicators from one intrusion rarely survive to the next,” the company’s security team wrote in a blog post. “The threat actor has historically demonstrated a high degree of operational security awareness, professional practices, and tradecraft.”

A BeyondTrust spokesperson declined to answer questions about how many customers are already compromised or why it didn’t publicly disclose the actively exploited zero-day sooner, and instead referred back to its security advisory. 

The company said the first known instance of zero-day exploitation occurred Aug. 29, which it detected and contained Sept. 28. 

BeyondTrust also said it detected the malicious activity after zero-days were confirmed to be exploited in another security vendor’s product Sept. 27. That timing matches a round of zero-days Citrix NetScaler disclosed, following nearly two days of rampant worry and unconfirmed rumors. 

BeyondTrust did not say if there is any link or overlap between the attacks targeting Citrix NetScaler, which went undetected for more than three weeks, and its remote access product. 

GTIG researchers said there isn’t enough evidence to assess an overall targeting trend, but encouraged all potentially vulnerable organizations to apply the patch and hunt for pre-disclosure activity. 

The threat group’s previous targets include business-process outsourcers, government, legal services, technology companies and software-as-a-service providers.

“Armory Castle remains one of the most prominent China-nexus threat actors due to its persistent targeting of various edge device technologies, use of zero-day vulnerabilities for widespread exploitation across multiple industries and regions, and its continuously expanding and evolving arsenal of tools,” said Dan Perez, technical lead at GTIG.

“This is a well-established pattern for Armory Castle,” Vanderlee said. “Targeting edge devices, which typically do not support endpoint detection and response (EDR), allows the threat actor to minimize opportunities for detection and maintain stealthy, persistent access to targeted networks.”

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Ivanti customers are in familiar territory, responding to yet another actively exploited zero-day affecting one of the vendor’s most commonly targeted security products. 

Volexity researchers, which discovered in-the-wild exploitation earlier this month, said attackers actually exploited three zero-days in a chain that allowed them to bypass authentication, execute code remotely and escalate privileges. 

Ivanti disclosed and issued a patch for the authentication bypass and remote-code execution components of the exploit chain as a single vulnerability in Ivanti Connect Secure. The company said it initially discovered a portion of the high-severity vulnerability — CVE-2026-104935 — during internal security checks in June.

A threat actor, which Volexity tracks as UTA0576, exploited the defects before Ivanti addressed them and issued a patch.

“Because the issue was discovered internally, was not being actively exploited, and did not meet the threshold for an out-of-band release, a fix was scheduled for inclusion in our normal product release cycle,” an Ivanti spokesperson wrote in response to questions.

“Successful exploitation requires chaining multiple vulnerabilities and Ivanti has fully addressed the unauthenticated remote code execution component of that chain, eliminating the primary exploitation path,” the spokesperson added. “We are also developing additional updates to address the remaining vulnerability and further strengthen product security.”

The full scope of compromise remains under investigation. The company, in a security advisory, said a “limited number of customers” were already compromised prior to disclosure. 

The Cybersecurity and Infrastructure Security Agency added the defect to its known exploited vulnerabilities catalog Tuesday.

Sean Koessel, vice president of professional services at Volexity, said the earliest confirmed instance of exploitation occurred Oct. 1. Yet, “it wouldn’t surprise us if there was activity toward the end of September,” he added.

Volexity researchers observed a series of post-exploitation activities during an investigation involving a customer’s compromised Ivanti Connect Secure VPN appliance earlier this month. “UTA0576 repeatedly exploited these vulnerabilities to compromise the ICS VPN appliance and run commands on it,” the company wrote in a blog post. 

The threat actor extracted credentials stored on the device, dumped and stole Active Directory metadata, and deployed multiple custom and malicious tools capable of facilitating follow-on attacks, credential testing and hunting for administrator passwords, recovery keys and other passwords.

“Based on Volexity’s observations, UTA0576 primarily focused on credential theft, data exfiltration, log tampering, and network reconnaissance,” the company added.

Ivanti encouraged potentially vulnerable customers to act immediately by upgrading to the latest version of software, running the company’s Integrity Checker Tool regularly, and reviewing indicators of compromise published by Volexity.

CISA also urged Ivanti customers to patch the vulnerability quickly, as it dissuaded customers from relying on the company’s Integrity Checker Tool.

“Organizations seeking to determine whether they were compromised will need to conduct network and memory forensics to identify evidence of exploitation,” the agency said in an alert Tuesday. “Ivanti’s Integrity Checker Tool may not detect evidence of exploitation of CVE-2026-104935 because threat actor commands execute in memory.”

Ivanti products, including Ivanti Connect Secure, are a frequent target for attackers of various motivations in the network edge space. 

CISA has flagged 36 Ivanti defects on its known exploited vulnerabilities catalog since late 2021. At least 6 defects across Ivanti products have been exploited since late January.

“Edge devices are a valuable initial foothold and often enable attackers to pivot further into targeted networks,” Koessel said. “It would be fair to expect widespread exploitation, this is a common theme with most vulnerabilities in edge devices.”

Other researchers also expect exploitation to pick up rapidly. 

“Given the history of attacker attention and focus Ivanti Connect Secure has previously drawn — and the trivial nature of the authentication bypass — widespread, indiscriminate exploitation is inevitable as attackers begin reviewing patches and public information,” said Yordan Ganchev, principal threat intelligence specialist at watchTowr.

“The race condition required for code execution offers little resistance, as an unauthenticated attacker can repeatedly attempt exploitation until it succeeds,” he added.

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