Threat Overview

On 2025-12-17 AlienVault released a new threat report titled UAT-9686 actively targets Cisco Secure Email Gateway and Secure Email and Web Manager. The report details a Chinese-nexus advanced persistent threat (APT) that has been operating since late November 2025. The actors, referred to as UAT-9686, focus on exploiting non‑standard configurations within Cisco AsyncOS software to gain system‑level access and deploy a persistent Python backdoor named AquaShell.

Actor Profile

UAT-9686 is a sophisticated threat actor with capabilities comparable to other well‑known Chinese APT groups. Their toolkit includes AquaShell, AquaTunnel, chisel, and AquaPurge, indicating a high level of operational security and a focus on stealth. The group demonstrates a clear intent to compromise email infrastructure, which is critical for both corporate and governmental communications.

Tactics, Techniques, and Procedures (TTPs)

• Initial Access: Exploit non‑standard AsyncOS configurations to execute system‑level commands.
• Execution: Deploy AquaShell, a Python‑based backdoor capable of executing encoded commands in the system shell.
• Persistence: Use AquaShell to maintain long‑term access and enable remote control.
• Command and Control: AquaTunnel and chisel facilitate reverse SSH and TCP/UDP tunneling, allowing the attackers to bypass network perimeter defenses.
• Defense Evasion: AquaPurge clears logs to obscure activity, while encoded command execution hides payloads from signature‑based detection.
• Impact: The backdoor can exfiltrate data, modify email routing, and potentially deliver malicious attachments or phishing content.

Detection Indicators

Security analysts should monitor for the following indicators of compromise (IOCs):

• Unexpected Python processes named AquaShell running under privileged accounts.
• Outbound connections to unfamiliar IP addresses on non‑standard ports, especially those associated with reverse tunneling.
• Alterations to AsyncOS configuration files or the presence of non‑standard scripts.
• Log clearing activity or sudden disappearance of audit logs.
• Encoded command strings within system shell logs.

Mitigation Recommendations

To defend against UAT-9686, organizations should implement a layered security approach:

• Verify and harden AsyncOS configurations. Disable any non‑standard features that are not required for business operations.
• Apply the latest Cisco patches and firmware updates to eliminate known vulnerabilities.
• Deploy endpoint detection and response (EDR) solutions that can detect Python backdoors and anomalous process behavior.
• Implement strict network segmentation. Restrict outbound traffic from email gateways to known, whitelisted destinations.
• Enable logging and monitoring for all system‑level command execution. Use a centralized SIEM to correlate events across the email infrastructure.
• Regularly audit and validate log integrity. Consider using immutable logging solutions to prevent log tampering.
• Educate administrators on the risks of enabling non‑standard configurations and the importance of least‑privilege principles.

Conclusion

The UAT-9686 campaign demonstrates a focused effort to compromise Cisco Secure Email Gateway and Web Manager environments. By leveraging non‑standard configurations and a sophisticated toolset, the threat actor can achieve persistence, evade detection, and potentially disrupt critical email services. Security teams must remain vigilant, enforce hardening best practices, and maintain robust monitoring to detect and respond to these advanced tactics before they can cause significant damage.