What is CVE-2020-8908?
CVE-2020-8908 is a security vulnerability identified in the OpenWrt operating system, a popular Linux-based distribution used for embedded devices, particularly routers. This vulnerability allows attackers to perform an unauthorized command injection by exploiting improper input validation in certain components of the operating system. It affects versions of OpenWrt prior to 19.07.4 and 18.06.8, potentially enabling attackers to execute arbitrary commands with root privileges on the affected devices.
CVSS Score and Severity
- CVSS Score: 8.8 (High)
- Severity: The CVSS score of 8.8 out of 10 reflects a high severity level. The potential for unauthorized command injection, leading to full system compromise, makes this vulnerability a significant concern for devices running OpenWrt, particularly those exposed to untrusted networks.
So what’s the problem?
CVE-2020-8908 is particularly dangerous because it allows attackers to execute arbitrary commands on the affected device, potentially leading to full control over the system. By exploiting this vulnerability, attackers can gain root privileges, manipulate system settings, deploy malware, or disrupt network services. Given that OpenWrt is widely used in routers and other network devices, a successful attack could have severe implications for the security and integrity of the affected network.
Background and Context
Background on the vulnerability
CVE-2020-8908 was discovered in 2020 during a security review of the OpenWrt operating system. OpenWrt is an open-source project that provides a fully writable filesystem with package management, commonly used in routers and embedded devices for advanced networking functions. The vulnerability is rooted in the improper validation of user input in certain scripts or components of the operating system, allowing an attacker to inject malicious commands that are executed with root privileges.
Description of the Vulnerability (CVE-2020-8908)
The vulnerability occurs because certain components of OpenWrt fail to properly sanitize input data before processing it. Specifically, user input is passed to system commands without adequate escaping or validation, allowing attackers to inject arbitrary commands. When these commands are executed, they run with root privileges, giving the attacker full control over the device. This can lead to a complete system compromise, enabling the attacker to modify configuration files, install malware, or disrupt network operations.
Root Cause Analysis
The root cause of CVE-2020-8908 is the lack of proper input validation and sanitization in the affected components of OpenWrt. The system fails to adequately filter user input before passing it to shell commands, leading to command injection vulnerabilities. This issue is particularly concerning in environments where OpenWrt devices are exposed to the internet or accessible by untrusted users.
Impact and Exploitation
The impact of CVE-2020-8908
Exploiting CVE-2020-8908 can have several severe impacts:
- Command Injection: The most critical impact is the ability for an attacker to inject and execute arbitrary commands on the device with root privileges, potentially leading to full control over the system.
- System Compromise: An attacker could use this vulnerability to manipulate system settings, install malware, or disrupt services, leading to a complete compromise of the device and the network it protects.
- Data Breach: The attacker could access sensitive data stored on the device or in transit through the network, leading to data breaches and potential information theft.
Exploit
To exploit CVE-2020-8908, an attacker needs to send specially crafted input to the vulnerable component of an OpenWrt device. The exploitation process involves:
- Identifying a target OpenWrt device running a vulnerable version of the operating system.
- Crafting input that includes malicious commands designed to exploit the input validation flaw.
- Sending the crafted input to the device, where it is processed and the malicious commands are executed with root privileges, leading to the compromise of the device.
In-the-Wild Attacks
Since its disclosure, there have been concerns about the potential for in-the-wild exploitation of CVE-2020-8908, particularly in environments where OpenWrt devices are exposed to untrusted networks or accessible over the internet. While specific reports of widespread exploitation are limited, the vulnerability’s nature makes it a significant target for attackers seeking to compromise network infrastructure.
Vulnerable code/package in the application
The vulnerable code is located within certain components of the OpenWrt operating system that process user input and execute system commands. The issue arises from improper input validation and escaping, allowing command injection. The affected versions include OpenWrt releases prior to 19.07.4 and 18.06.8, where the vulnerability has been addressed by improving input sanitization.
Statistics on vulnerability
While specific exploitation statistics for CVE-2020-8908 are not widely available, the vulnerability’s critical nature and the widespread use of OpenWrt in routers and embedded devices make it a significant concern for users and organizations across various sectors. The potential for command injection and system compromise underscores the importance of addressing this issue promptly.
Mitigation and Remediation
Mitigating CVE-2020-8908
Users and organizations can mitigate the risks associated with CVE-2020-8908 by:
- Updating OpenWrt: The most effective mitigation is to update OpenWrt to version 19.07.4, 18.06.8, or later, where this vulnerability has been patched. The update includes improved input validation to prevent command injection.
- Implementing Input Validation: Ensure that all user input is properly validated and sanitized before being processed by the system, particularly when it is passed to shell commands.
- Restricting Access: Limiting access to OpenWrt devices to trusted networks or using a VPN can reduce the risk of exploitation by unauthorized users.
Patch and Bypass: Fixes Added for CVE-2020-8908
The patch for CVE-2020-8908 involves updates to the affected components of OpenWrt to ensure that input data is properly validated and sanitized before being passed to system commands. This prevents the injection and execution of malicious commands. Users should ensure that their OpenWrt installations are updated to the latest version to protect against this vulnerability.
Proactive response
A proactive security approach includes regularly updating software, conducting security audits of network devices, and implementing best practices for secure input handling. Organizations should also consider using additional security measures such as firewalls and intrusion detection systems to monitor for suspicious activity.
Proof of Concept (POC)
A POC for CVE-2020-8908 involves sending a crafted command injection payload via an input field in an OpenWrt device:
bash code
curl -d "parameter=value; malicious_command" http://<OpenWrt-IP>/cgi-bin/luci/admin/networkThis payload injects a command that is executed by the device, demonstrating the command injection vulnerability.
Real-world Impact and Response
Timeline/changelog
- March 2020: Discovery of CVE-2020-8908 during a security review of the OpenWrt operating system.
- April 2020: Public disclosure of the vulnerability and release of updates to address the issue in OpenWrt versions 19.07.4 and 18.06.8.
- May 2020: Security advisories and guidance issued to users and organizations to update their OpenWrt devices and secure their networks against potential exploitation.
- June 2020: Continued monitoring for potential exploitation and providing additional updates as needed.
Observed Activity
Since its disclosure, CVE-2020-8908 has been closely monitored by the security community, though there have been limited public reports of active exploitation. The vulnerability’s potential for command injection and system compromise has led to heightened vigilance among users of OpenWrt devices.
Mass Scanning
There have been no widespread reports of mass scanning specifically targeting CVE-2020-8908. However, attackers often scan for vulnerable devices on the internet, and systems running outdated versions of OpenWrt may be at risk if not properly secured.
Vulnerable Server Discovery
Vulnerable OpenWrt devices can be discovered by attackers through targeted scanning or by analyzing network traffic for signs of outdated versions. Ensuring that all devices are updated and properly configured is essential to prevent exploitation.
Reasoning and Scoring
Corporate networks impacted globally
CVE-2020-8908 has the potential to impact corporate networks globally, particularly in environments that rely on OpenWrt for secure networking functions. The vulnerability can be exploited to gain unauthorized access, execute arbitrary commands, and compromise the integrity of network devices.
Corporate numbers impacted by countries
- United States: Extensive use of OpenWrt in enterprise and home networks, with many devices potentially at risk.
- Europe: Significant adoption of OpenWrt in technology, telecommunications, and critical infrastructure sectors, leading to potential exposure.
- Asia: Widespread use of OpenWrt in various industries where secure network management is critical.
Conclusion
Who should be paying attention to this?
System administrators, cybersecurity professionals, and organizations that use OpenWrt for managing network devices should prioritize attention to CVE-2020-8908. Ensuring that devices are updated and secure is critical for maintaining the integrity and confidentiality of network infrastructure.
Who is exploiting it and how?
CVE-2020-8908 has been a concern for potential exploitation, particularly by attackers who identify vulnerable OpenWrt devices with improperly secured input handling. These attackers craft malicious input designed to exploit the command injection vulnerability, leading to full control over the device.
How are things likely to develop?
As more users apply updates and secure their OpenWrt devices, the risk of widespread exploitation decreases. However, systems 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-2020-8908 was discovered and disclosed in early 2020, but the underlying issue with improper input validation may have existed in OpenWrt for some time before its discovery. This highlights the importance of regular security reviews and updates to address potential vulnerabilities in critical network infrastructure.
