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Image: Cisco Talos (fair use).

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Cisco Talos Says UAT-11473 Hid a Malware Framework Inside Cisco SD-WAN Controllers to Collect IPsec Key Material, Using Infrastructure That Overlaps Volt Typhoon's Silent Train Network

The KeyDrift framework came in through CVE-2026-20127, an authentication bypass in Catalyst SD-WAN Controller, then injected itself into the vdaemon control-plane process and hooked decrypted traffic, Talos said. Targets included space and satellite services, defense and aerospace technology and policy research, and Talos published Snort coverage and file paths defenders can check now.

Priya Shah, Threat IntelSingapore5 min read

SINGAPORE - A highly sophisticated hacking group broke into Cisco SD-WAN controllers through an authentication bypass and planted a custom malware framework inside the software that runs the network's control plane, where it intercepted decrypted traffic and collected encryption key material, Cisco Talos said in a report published Wednesday.

Talos tracks the group as UAT-11473 and the framework as KeyDrift. The intrusions exploited CVE-2026-20127, an authentication bypass in Cisco SD-WAN Catalyst Controller instances, and the targets spanned space and satellite services, defense and aerospace technology, and policy research. "Talos assesses with high confidence that UAT-11473's operating infrastructure overlaps considerably with Volt Typhoon's 'Silent Train' covert access network," the report says, linking the activity to the disposable relay network that Lumen's Black Lotus Labs exposed this week.

Living inside the control plane

KeyDrift's main component, which Talos calls PolyFlame, is a memory-resident module injected into running vdaemon processes, the controller daemons that handle SD-WAN control traffic. From there it hooks socket, DTLS and dynamic linker functions, giving the attackers access to session keys, edge topology, routes and policy tables. PolyFlame doubles as a TinyShell-style backdoor that can run commands and read or write files, and as an intermediate command server that relays tasking to other compromised peers.

Malicious aaamgr runit launcher recovered from an affected vBond appliance, with highlighted lines that remount the writable overlay as executable and start the packed aaamgrd loader.
Image: Cisco Talos (fair use).The trojanized aaamgr service launcher, with the attacker's added lines in red.

Talos recovered no hardcoded IP addresses, ports, domains or polling intervals from PolyFlame. The implant is built to take orders in-band, over the SD-WAN control-plane traffic itself, rather than beaconing to a fixed external server. Before acting on a command, it checks that the server has sent the MD5 hash of the device's current date, and stops if the values do not match.

A second module, LittleFilch, hooks the SSL_read function inside vdaemon and inspects decrypted control-plane messages for three byte patterns. Behind them sit an edge device's public transport IP, its system IP and a 32-byte field that Talos assesses is AES-256 IPsec key material distributed for the data plane, the encryption that protects traffic between an organization's SD-WAN sites. LittleFilch encrypts what it collects with RSA, writes it to /var/tmp/vdaemon.bin and can send it out over UDP in records formatted to look like DTLS 1.2 application data.

What to check on controllers

The framework anchors itself in the controller's runit service scripts, which gives defenders specific places to look. In one variant, the attackers modified the sshd run script to remount /rootfs.rw as executable and launch a script named conf_sshd, which records vdaemon process IDs in /tmp/system-vdaemon and calls an injector, rsshd, to load PolyFlame as libdssl.so. In another, a malicious service under /etc/sv/aaamgr/ runs a packed ELF called aaamgrd. Talos noted that the legitimate Cisco aaamgr component is a Python package and does not normally appear as a compiled ELF runit service.

Recovered operator staging commands that copy the malicious aaamgr files into place, set permissions and use touch and chmod with the reference option to copy timestamps from legitimate files.
Image: Cisco Talos (fair use).The staging sequence, including the timestomping commands Talos flagged.

The staging commands Talos recovered also used touch and chmod with the reference option, copying metadata from legitimate files so the implants would blend in. LittleFilch reads its endpoint settings from /var/tmp/vdaemon.conf and deletes that file after reading it; Talos has not been able to recover it. Variations among the samples, the report says, suggest the framework is under active development.

Shell loop from the conf_sshd script that finds each running vdaemon process, records its ID in /tmp/system-vdaemon and calls rsshd to inject libdssl.so.
Image: Cisco Talos (fair use).The injection loop that loads PolyFlame into every vdaemon process.

Cisco has released patches for CVE-2026-20127 and a hardening guide for Catalyst SD-WAN deployments, and Talos urged organizations to apply them and to monitor for signs of post-compromise activity. Because KeyDrift lives inside legitimate daemons and talks over the control plane, a patched controller is not proof of a clean one. Teams running Catalyst SD-WAN should compare runit service scripts under /etc/sv/ against known-good versions, look for an ELF binary in the aaamgr service path and for the vdaemon files named in the report, and treat any confirmed hit as an incident that warrants a Cisco TAC case and rotation of the keys the controller distributes.

Snort rules 65938 and 65958 cover exploitation of CVE-2026-20127. For the KeyDrift artifacts, Talos published Snort 2 rules 67387 through 67416 and Snort 3 rules 7:44 through 7:73.

Sources:


Priya Shah covers threat intelligence, intrusion analysis, and adversary tradecraft for SOCtember from Singapore.

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