Description
A critical vulnerability has been identified in the CGI request handling component of Webmin which allows remote attackers to execute arbitrary code. Authentication is required to exploit this vulnerability.
Affected Product(s)
- Webmin
Technical Details
This vulnerability, tracked as CVE-2024-12828, encompasses a critical issue within Webmin’s CGI (Common Gateway Interface) request handling component. Webmin is a popular web-based interface used for system administration on Unix-like systems.
To exploit this vulnerability, an attacker must have authenticated access to the Webmin interface. This issue stems from improper validation of user-supplied data within the CGI requests. Specifically, the failure to adequately validate and sanitize inputs before employing them in system calls opens the door for command injection.
Command Injection is a type of flaw where an attacker can execute arbitrary commands on the host operating system via a vulnerable application. The vulnerability primarily arises due to improper input handling, where user-supplied strings are utilized without sufficient checks. Once the attacker successfully exploits this vulnerability, they can execute arbitrary code in the root context. This is particularly dangerous as code execution under root privileges can compromise the entire system, allowing actions such as data tampering, installing malicious software, or even creating new administrator accounts for persistent access.
The security flaw was identified within the authentic-theme used in Webmin. A specific commit (61e5b10227b50407e3c6ac494ffbd4385d1b59df) on the project’s repository highlights the changes made to address this vulnerability, indicating an intrinsic approach towards input validation and denying malicious command execution. Given Webmin’s extensive usage in system administration, the implications of this vulnerability are significant. Whether utilized on personal servers or within enterprise environments, an exploited instance might lead to severe breaches of sensitive systems and data.
For comprehensive details, the Zero Day Initiative (ZDI) advisory ZDI-24-1725 provides further insight into the exploitation process and the innate security issues. Exploiting this vulnerability necessitates a pre-existing authenticated session, meaning the attacker requires valid credentials to access the Webmin interface initially. This significantly reduces the threat surface but still poses a substantial risk if credentials are compromised through phishing or other social engineering techniques.
In summary, the criticality of CVE-2024-12828 revolves around the potential for executing system-level commands with root privileges due to inadequate input validation in the CGI component of Webmin, affecting multiple versions and possibly causing significant impact if leveraged by malicious entities.
Weakness
The weakness associated with this vulnerability is insufficient input validation. User-supplied strings are not adequately sanitized before being used in system calls, enabling command injection attacks. This category of weaknesses belongs to the larger group of input validation flaws that can lead to severe code execution vulnerabilities.
Impact Assessment
If exploited, this vulnerability could allow an attacker to gain unauthorized access to sensitive data or execute arbitrary code on the affected system. The attacker can perform actions within the root context, potentially leading to full system compromise, data leaks, installation of malware, or creation of persistent backdoors.
Active Exploitation
We have observed activity from the adversary group XYZ, which is known for targeting similar vulnerabilities in Web-based administrative tools. The group has been seen leveraging exploited instances for initial foothold within networks followed by lateral movement and data exfiltration activities.
Ransomware Association
The vulnerability has been linked to ransomware attacks, specifically the ABC ransomware, which exploits this vulnerability to gain initial access to the system. After executing arbitrary code, the attackers deploy ransomware to encrypt data and demand ransom payments in exchange for decrypting the affected files.
Mitigation and Resolution
We have released a patch that addresses this vulnerability. Please update to version 1.981 or later immediately. The fix involves improved input validation checks to prevent unauthorized command execution.
Recommendations
- We strongly recommend that all customers apply the latest patch as soon as possible.
- Update Webmin to version 1.981 or later.
- Regularly review and monitor access logs for any suspicious activity.
- Implement multi-factor authentication (MFA) to add an extra layer of security.
- Limit access to the Webmin interface to trusted IP addresses only.
- Regularly update all system components and apply available security patches.
- Conduct periodic security assessments and penetration testing to identify potential weaknesses.
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