CVE-2021-27289

Comprehensive Technical Analysis of CVE-2021-27289

1. Vulnerability Assessment and Severity Evaluation

CVE ID: CVE-2021-27289 CVSS Score: 9.1

The vulnerability in question is a replay attack vulnerability affecting the Zigbee smart home kit manufactured by Ksix. The improper implementation of the Zigbee anti-replay mechanism, specifically the frame counter field, allows an attacker to resend captured packets with a higher sequence number. This flaw enables the attacker to inject spoofed commands without authentication, leading to false alerts and misleading notifications in the associated mobile application.

Severity Evaluation:

• CVSS Score: 9.1 (Critical)
• Impact: High
• Exploitability: High

The high CVSS score indicates a critical vulnerability that can be easily exploited with significant impact on the integrity and availability of the affected systems.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

1. Wireless Range Attack: An attacker within wireless range can capture Zigbee packets and resend them with modified sequence numbers.
2. Spoofing: The attacker can inject spoofed commands, leading to false alerts and misleading notifications.
3. Denial of Service (DoS): Continuous injection of spoofed commands can overwhelm the system, leading to a DoS condition.

Exploitation Methods:

1. Packet Capture: Using tools like Wireshark or specialized Zigbee sniffers to capture Zigbee packets.
2. Packet Modification: Modifying the captured packets to increase the sequence number.
3. Packet Injection: Resending the modified packets to the Zigbee network using tools like KillerBee or custom scripts.

3. Affected Systems and Software Versions

Affected Systems:

• Zigbee Gateway Module (v1.0.3)
• Door Sensor (v1.0.7)
• Motion Sensor (v1.0.12)

Software Versions:

• The specific firmware versions mentioned above are vulnerable.

4. Recommended Mitigation Strategies

1. Firmware Update: Immediately update the firmware of the affected devices to a version that properly implements the Zigbee anti-replay mechanism.
2. Network Segmentation: Segment the Zigbee network from other critical networks to limit the impact of a potential attack.
3. Encryption: Ensure that all communications within the Zigbee network are encrypted to prevent packet capture and modification.
4. Monitoring: Implement continuous monitoring and anomaly detection to identify and respond to suspicious activities.
5. Access Control: Limit physical access to the Zigbee network to trusted individuals only.

5. Impact on Cybersecurity Landscape

The discovery of this vulnerability highlights the importance of robust security mechanisms in IoT devices. The Zigbee protocol, widely used in smart home and industrial IoT applications, must be carefully implemented to prevent such critical vulnerabilities. This incident underscores the need for:

• Stronger Security Standards: Ensuring that IoT devices comply with stringent security standards.
• Regular Audits: Conducting regular security audits and penetration testing of IoT devices.
• User Awareness: Educating users about the risks associated with IoT devices and the importance of keeping firmware up to date.

6. Technical Details for Security Professionals

Vulnerability Details:

• Frame Counter Field: The frame counter field in Zigbee packets is used to prevent replay attacks. Each packet should have a unique, incrementing counter value.
• Improper Implementation: In the affected Ksix devices, the frame counter field is not properly incremented or checked, allowing packets with higher sequence numbers to be accepted as legitimate.

Exploitation Steps:

1. Capture Packets: Use a Zigbee sniffer to capture packets from the network.
2. Modify Sequence Number: Increase the sequence number in the captured packets.
3. Inject Packets: Resend the modified packets to the Zigbee network.

Detection and Response:

• Intrusion Detection Systems (IDS): Deploy IDS to detect anomalous Zigbee traffic.
• Log Analysis: Regularly analyze logs for unusual patterns or repeated packets.
• Incident Response Plan: Develop and implement an incident response plan specific to IoT devices.

References:

• GitHub Repository
• Packet Storm Security
• Exploit Database
• [YouTube Videos](https://www.youtube.com/watch?v=5IFUpRKEioA, https://www.youtube.com/watch?v=XFOy3wSlC9Q, https://www.youtube.com/watch?v=yc9IEt5IMmA)

By addressing this vulnerability promptly and implementing robust security measures, organizations can mitigate the risks associated with replay attacks in Zigbee networks.