Enterprise security teams rely on EDR tools like Palo Alto Networks’ Cortex XDR to detect, investigate, and respond to threats. But a new research finding shows that the Live Terminal feature—designed for remote endpoint management—can be repurposed by attackers as a stealthy command-and-control (C2) channel.
This vulnerability is particularly concerning because it leverages trusted EDR traffic, which often bypasses inspection and detection mechanisms. Organizations using Cortex XDR must understand how attackers exploit this feature, the potential impact on enterprise security, and the mitigation strategies needed to stay protected.
In this article, we break down the research findings, attack techniques, and practical steps for defending against this risk.
Understanding Cortex XDR Live Terminal
What is Live Terminal?
Cortex XDR’s Live Terminal is a legitimate remote management tool that enables security teams to:
- Execute commands on endpoints
- Run PowerShell and Python scripts
- Browse files and manage processes
- Connect to endpoints via a centralized console
It communicates through WebSocket connections to Palo Alto’s cloud infrastructure, enabling administrators to manage endpoints securely and efficiently.
How Attackers Exploit Live Terminal
The Vulnerability
Researchers at InfoGuard Labs discovered that Live Terminal has no command signing, meaning the system does not verify whether instructions come from a legitimate administrator.
- Intercepted WebSocket messages can redirect endpoints to attacker-controlled servers
- The cortex-xdr-payload.exe client component is trusted by the EDR, allowing commands to bypass traditional detection
This method exemplifies a “Living off the Land” attack, where threat actors use existing tools instead of introducing new malware, reducing noise and detection risk.
Attack Methods
1. Cross-Tenant Attack
- Attacker uses their own Cortex tenant to generate a valid session token
- Redirects the victim’s endpoint to connect to the attacker-controlled tenant
- Grants full Live Terminal access through the official GUI
2. Custom Server Exploit
- Attacker replicates the WebSocket protocol on a custom server
- Minimal development effort is needed based on intercepted traffic
- Commands issued via this channel appear as legitimate Cortex traffic
Technical Flaws
Researchers decompiled cortex-xdr-payload.exe (a Python 3.12 app) and found a critical flaw in server address validation:
- The function
run_lrc_payloadchecks that the server ends with.paloaltonetworks.com - The check is performed on the full URL, allowing crafted URLs like
attacker.com/test.paloaltonetworks.comto bypass validation
Parent Process Monitoring:
- Legitimate parent process:
cyserver.exe - Any deviation should be treated as suspicious
Security Implications
- Stealthy Persistence: Attackers maintain hidden control over endpoints without deploying additional tools
- Bypassing Detection: Traffic blends in with legitimate Cortex agent communication and often avoids TLS inspection
- Lateral Movement & Data Exfiltration: Attackers can issue commands, move across systems, and collect sensitive files undetected
- Enterprise Risk: Any organization using Cortex XDR is at risk if initial access is gained
Real-World Observations
- Researchers tested version 8.9.1 with the latest content updates (Feb 23, 2026) and found the abuse still effective, despite prior patches in versions 8.7–8.9
- Security teams relying solely on detection rules based on parent processes are insufficient
- Mitigation requires architectural changes, not just monitoring
Recommended Mitigation Strategies
1. Monitor Process Creation Events
- Flag any
cortex-xdr-payload.exeinstances not launched bycyserver.exe
2. Harden WebSocket Communications
- Advocate for mutual authentication and cryptographic command signing at the protocol level
3. Implement Layered Controls
- Combine endpoint monitoring with network-level traffic analysis to detect anomalous patterns
4. Update and Patch Regularly
- Ensure Cortex XDR agents are running the latest versions with all content updates
5. Review Threat Detection Policies
- Adjust SIEM and SOC rules to account for potential misuse of trusted EDR channels
Tools and Frameworks
- MITRE ATT&CK – Map Living-off-the-Land techniques (T1071, T1059)
- NIST Cybersecurity Framework – Integrate controls for monitoring, detection, and incident response
- EDR Forensics – Decompile and analyze client binaries for anomalies
Expert Insights
- Practical Recommendation: Organizations should not rely solely on detection; architectural fixes at the protocol level are required
- Risk Analysis: Successful exploitation provides attackers a quiet, persistent foothold, increasing the likelihood of lateral movement and data exfiltration
- Compliance Relevance: Undetected C2 activity could compromise frameworks such as ISO 27001, HIPAA, and SOC 2
FAQs
Q1: Can attackers exploit Cortex XDR Live Terminal without malware?
A1: Yes. The attack leverages existing trusted components (cortex-xdr-payload.exe) and requires no additional malware.
Q2: Which Cortex XDR versions are vulnerable?
A2: Versions 8.7 through 8.9.1 are affected; testing shows prior fixes were insufficient.
Q3: How can organizations detect abuse?
A3: Monitor parent processes and anomalous WebSocket connections, but detection-only methods are limited.
Q4: What are the mitigation options?
A4: Patch agents, enforce process controls, implement mutual authentication, and advocate for cryptographic command signing in Live Terminal.
Q5: Why is this attack considered “Living off the Land”?
A5: Attackers use tools already trusted by the EDR, avoiding new malware deployment and reducing detection noise.
Conclusion
The abuse of Cortex XDR Live Terminal illustrates a key cybersecurity principle: even trusted security tools can be weaponized if their design lacks cryptographic verification. Enterprises must go beyond detection-only approaches, monitoring process behavior, hardening communications, and pushing vendors toward secure-by-design protocol implementations.
CTA: Conduct an EDR security audit today to identify potential misuse of trusted channels and ensure your Cortex XDR deployment is resilient against stealthy C2 attacks.
