What is CVE-2020-8515?
CVE-2020-8515 is a critical security vulnerability found in DrayTek Vigor enterprise routers, specifically in the web management interface of these devices. This vulnerability allows remote attackers to execute arbitrary code on the affected routers by sending specially crafted requests to the vulnerable interface. It affects several models of DrayTek Vigor routers, posing a significant threat to network security, particularly in environments where these routers are used to manage critical business communications and data traffic.
CVSS Score and Severity
- CVSS Score: 9.8 (Critical)
- Severity: The CVSS score of 9.8 out of 10 reflects the critical nature of this vulnerability. The ability to remotely execute arbitrary code on enterprise routers can lead to full network compromise, making this a severe issue for organizations using vulnerable DrayTek devices.
So what’s the problem?
CVE-2020-8515 is particularly dangerous because it allows attackers to take full control of the affected router, enabling them to intercept, manipulate, or reroute network traffic. An attacker could exploit this vulnerability to deploy malware, establish persistent backdoors, or disrupt network services entirely. Given the critical role that routers play in managing network traffic and maintaining security boundaries, this vulnerability poses a serious risk to the integrity and confidentiality of an organization’s network.
Background and Context
Background on the vulnerability
CVE-2020-8515 was discovered in early 2020 and affects the web management interface of certain DrayTek Vigor routers. DrayTek Vigor routers are widely used in small to medium-sized enterprises for their robust networking features, including VPN support, firewall capabilities, and multi-WAN load balancing. The vulnerability arises from improper input validation in the web management interface, which allows attackers to send specially crafted requests that bypass authentication and execute arbitrary commands on the router’s operating system.
Description of the Vulnerability (CVE-2020-8515)
The vulnerability occurs because the web management interface of the affected DrayTek routers does not properly validate incoming HTTP requests. Specifically, certain parameters within the requests are not adequately sanitized, allowing an attacker to inject and execute arbitrary commands on the router’s operating system. This could lead to the complete compromise of the router, including the ability to intercept, modify, or reroute network traffic passing through the device.
Root Cause Analysis
The root cause of CVE-2020-8515 is the failure to properly sanitize input in the web management interface of DrayTek Vigor routers. The lack of proper validation allows attackers to manipulate HTTP request parameters in a way that bypasses authentication checks and executes arbitrary code. This vulnerability is exacerbated in environments where the web management interface is exposed to the internet or accessible by untrusted users.
Impact and Exploitation
The impact of CVE-2020-8515
Exploiting CVE-2020-8515 can have several severe impacts:
- Remote Code Execution: The most critical impact is the ability for an attacker to execute arbitrary commands on the router, potentially leading to full control over the device.
- Network Traffic Interception: An attacker could use the compromised router to intercept, monitor, and manipulate all network traffic passing through the device, leading to data breaches and information theft.
- Service Disruption: By executing arbitrary code, the attacker could disrupt network services, reroute traffic, or create persistent backdoors, leading to significant operational downtime.
Exploit
To exploit CVE-2020-8515, an attacker needs to send a specially crafted HTTP request to the vulnerable web management interface of a DrayTek Vigor router. The exploitation process involves:
- Identifying a target DrayTek Vigor router with the web management interface exposed to the internet.
- Crafting an HTTP request that includes malicious parameters designed to exploit the input validation flaw.
- Sending the crafted request to the router, which processes the malicious input and executes the attacker’s commands, leading to the compromise of the device.
In-the-Wild Attacks
Since its disclosure, CVE-2020-8515 has been actively exploited in the wild. Attackers have targeted vulnerable DrayTek routers, particularly those exposed to the internet, to gain unauthorized access, deploy malware, and create persistent backdoors. The widespread use of these routers in business environments has made this vulnerability a popular target for attackers.
Vulnerable code/package in the application
The vulnerable code is located within the web management interface of several DrayTek Vigor router models. The affected models include, but are not limited to, the DrayTek Vigor 2960, 3900, and 300B routers. The vulnerability stems from improper input validation in the HTTP request handling mechanism, which allows attackers to inject and execute arbitrary commands.
Statistics on vulnerability
While specific exploitation statistics for CVE-2020-8515 are not widely available, the vulnerability’s critical nature and the extensive use of DrayTek routers in enterprise environments make it a significant concern for organizations across various industries. The potential for remote code execution and network compromise underscores the importance of addressing this issue promptly.
Mitigation and Remediation
Mitigating CVE-2020-8515
Organizations can mitigate the risks associated with CVE-2020-8515 by:
- Applying Firmware Updates: DrayTek has released firmware updates to address this vulnerability. It is critical to update all affected routers to the latest firmware versions to prevent exploitation.
- Restricting Access to the Web Interface: Limiting access to the web management interface to trusted IP addresses or using a VPN can reduce the risk of exploitation by unauthorized users.
- Disabling Remote Management: If remote management is not necessary, disabling it can help prevent attackers from exploiting this vulnerability over the internet.
Patch and Bypass: Fixes Added for CVE-2020-8515
The patch for CVE-2020-8515 involves updates to the web management interface to ensure that input parameters are properly validated and sanitized before being processed. This prevents malicious input from being executed as arbitrary commands on the router. Organizations should ensure that all DrayTek routers are updated to the latest firmware version to protect against this vulnerability.
Proactive response
A proactive security approach includes regularly updating firmware, conducting security audits of network devices, and implementing best practices for securing router management interfaces. Organizations should also consider segmenting their networks and using additional security measures such as firewalls and intrusion detection systems to monitor for suspicious activity.
Proof of Concept (POC)
A POC for CVE-2020-8515 might involve sending a crafted HTTP request to the vulnerable DrayTek router’s web management interface:
bash code–
curl -k "https://<Router-IP>/cgi-bin/mainfunction.cgi" -d "command=malicious_command"This request injects a command that is executed by the router, demonstrating the vulnerability.
Real-world Impact and Response
Timeline/changelog
- January 2020: Discovery of CVE-2020-8515 during a security review of DrayTek Vigor routers.
- February 2020: Public disclosure of the vulnerability and release of firmware updates by DrayTek to address the issue.
- March 2020: Security advisories and guidance issued to organizations to update their routers and secure their networks against potential exploitation.
- April 2020: Continued monitoring for potential exploitation and providing additional updates as needed.
Observed Activity
Since its disclosure, CVE-2020-8515 has been actively targeted by attackers, particularly in environments where DrayTek routers are exposed to the internet. Exploitation has led to the compromise of network traffic, the deployment of malware, and the creation of persistent backdoors on affected devices.
Mass Scanning
Following the disclosure of CVE-2020-8515, there has been an increase in scanning activity targeting DrayTek routers, particularly looking for devices with exposed web management interfaces. Attackers use automated tools to identify and exploit vulnerable routers.
Vulnerable Server Discovery
Vulnerable routers can be discovered by attackers through targeted scanning or by analyzing network traffic for signs of outdated firmware versions. Ensuring that all routers are updated and properly configured is essential to prevent exploitation.
Reasoning and Scoring
Corporate networks impacted globally
CVE-2020-8515 has the potential to impact corporate networks globally, particularly in industries that rely heavily on DrayTek routers for secure network management. The vulnerability can be exploited to gain unauthorized access, execute arbitrary code, and compromise the integrity of network communications.
Corporate numbers impacted by countries
- United States: Extensive use of DrayTek routers in small to medium-sized enterprises, with many organizations potentially at risk.
- Europe: Significant adoption of DrayTek routers in technology, finance, and critical infrastructure sectors, leading to potential exposure.
- Asia: Widespread use of DrayTek routers in industries where secure network management is critical.
Conclusion
Who should be paying attention to this?
Network administrators, cybersecurity professionals, and organizations that use DrayTek Vigor routers for managing network traffic should prioritize attention to CVE-2020-8515. Ensuring that routers are updated and secure is critical for maintaining the integrity and confidentiality of network communications.
Who is exploiting it and how?
CVE-2020-8515 has been exploited by attackers who identify vulnerable DrayTek routers with exposed web management interfaces. These attackers craft malicious HTTP requests designed to exploit the input validation flaw, leading to remote code execution and full control over the device.
How are things likely to develop?
As more organizations apply firmware updates and secure their routers, the risk of widespread exploitation decreases. However, devices that remain unpatched are still vulnerable to attack, and the potential for targeted exploitation remains a concern. Continuous vigilance and adherence to security best practices are essential to prevent exploitation.
How long has it been around?
CVE-2020-8515 was discovered and disclosed in early 2020, but the underlying issue with improper input validation may have existed in DrayTek Vigor routers for some time before its discovery. This highlights the importance of regular security reviews and updates to address potential vulnerabilities in critical network infrastructure.
