Description
user_login.cgi on Draytek Vigor2620 devices before 3.9.8.4 (and on all versions of Vigor2925 devices) allows attackers to send a crafted payload to modify the content of the code segment, insert shellcode, and execute arbitrary code.
EPSS Score:
1%
Comprehensive Technical Analysis of EUVD-2023-35755
1. Vulnerability Assessment and Severity Evaluation
The vulnerability EUVD-2023-35755, also known as CVE-2023-31447, affects the user_login.cgi script on Draytek Vigor2620 devices before version 3.9.8.4 and all versions of Vigor2925 devices. This vulnerability allows attackers to send a crafted payload to modify the content of the code segment, insert shellcode, and execute arbitrary code.
Severity Evaluation:
- CVSS Base Score: 9.8 (Critical)
- CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The high base score indicates a critical vulnerability due to the following factors:
- Attack Vector (AV:N): Network-based attack, meaning it can be exploited remotely.
- Attack Complexity (AC:L): Low complexity, indicating that the attack is relatively easy to execute.
- Privileges Required (PR:N): No privileges are required to exploit the vulnerability.
- User Interaction (UI:N): No user interaction is required.
- Scope (S:U): Unchanged, meaning the vulnerability does not affect other systems.
- Confidentiality (C:H), Integrity (I:H), and Availability (A:H): High impact on all three CIA triad components.
2. Potential Attack Vectors and Exploitation Methods
Attack Vectors:
- Remote Code Execution (RCE): Attackers can send a specially crafted payload to the
user_login.cgiscript, which allows them to modify the code segment and execute arbitrary code. - Shellcode Injection: The ability to insert and execute shellcode can lead to complete control over the affected device.
Exploitation Methods:
- Network-Based Attacks: Given the low complexity and network-based attack vector, attackers can exploit this vulnerability over the internet.
- Automated Scripts: Attackers can use automated scripts to scan for vulnerable devices and exploit them en masse.
3. Affected Systems and Software Versions
Affected Devices:
- Draytek Vigor2620 devices before version 3.9.8.4
- All versions of Draytek Vigor2925 devices
Software Versions:
- Any firmware version of Vigor2620 before 3.9.8.4
- All firmware versions of Vigor2925
4. Recommended Mitigation Strategies
Immediate Actions:
- Patch Management: Upgrade Draytek Vigor2620 devices to version 3.9.8.4 or later. For Vigor2925 devices, apply any available patches or updates from the vendor.
- Network Segmentation: Isolate affected devices from critical networks to limit the potential impact of an attack.
- Firewall Rules: Implement strict firewall rules to restrict access to the
user_login.cgiscript.
Long-Term Strategies:
- Regular Audits: Conduct regular security audits and vulnerability assessments.
- Intrusion Detection Systems (IDS): Deploy IDS to monitor for suspicious activities and potential exploitation attempts.
- User Education: Educate users on the importance of keeping devices updated and the risks associated with unpatched systems.
5. Impact on European Cybersecurity Landscape
The vulnerability poses a significant risk to the European cybersecurity landscape, particularly for organizations and individuals using Draytek devices. The ability to execute arbitrary code remotely can lead to data breaches, unauthorized access, and potential disruption of services. Given the widespread use of Draytek routers in both home and enterprise environments, the impact could be extensive if not addressed promptly.
6. Technical Details for Security Professionals
Technical Analysis:
- Vulnerable Component:
user_login.cgiscript - Exploitation Mechanism: The vulnerability allows attackers to inject shellcode into the code segment, leading to arbitrary code execution.
- Payload Crafting: Attackers can craft a payload that exploits the vulnerability by sending it to the
user_login.cgiscript.
Detection and Response:
- Log Analysis: Monitor logs for unusual activities related to the
user_login.cgiscript. - Anomaly Detection: Implement anomaly detection mechanisms to identify deviations from normal behavior.
- Incident Response: Develop and maintain an incident response plan to quickly address any detected exploitation attempts.
References:
By addressing this vulnerability promptly and implementing robust security measures, organizations can mitigate the risks associated with EUVD-2023-35755 and enhance their overall cybersecurity posture.