Critical Stack Overflow in Circutor SGE-PLC: CVE-2025-11786 Demands Immediate Attention

Overview

CVE-2025-11786 describes a critical stack-based buffer overflow vulnerability affecting Circutor SGE-PLC1000 and SGE-PLC50 programmable logic controllers (PLCs) running firmware version 9.0.2. This vulnerability allows a remote attacker to execute arbitrary shell commands with the same privileges as the application, potentially leading to complete system compromise. Given the role PLCs play in industrial control systems (ICS), the potential impact of this vulnerability is significant.

Technical Details

The vulnerability lies within the SetUserPassword() function. The newPassword parameter, which is intended to be the user’s new password, is directly incorporated into a shell command string using the sprintf() function. Critically, there is no input sanitization or validation performed on the newPassword parameter before it is used in the sprintf() call. The resulting command string is then executed using the system() function.

This lack of sanitization allows an attacker to inject arbitrary shell commands by crafting a newPassword that contains malicious code. Since system() executes the command with the privileges of the application, a successful exploit grants the attacker complete control over the PLC.

Vulnerable Code Snippet (Illustrative):

            char command[256];
            char newPassword[USER_PASSWORD_MAX_LENGTH]; // USER_PASSWORD_MAX_LENGTH is likely insufficient

            // ... receive newPassword from network ...

            sprintf(command, "some_system_utility -u user -p %s", newPassword);
            system(command);
        

The key issue is that if newPassword exceeds the available buffer size in command (e.g., 256 bytes), a stack-based buffer overflow will occur, overwriting adjacent memory and potentially hijacking control flow to execute attacker-supplied code.

CVSS Analysis

Unfortunately, a CVSS score and severity rating are not currently available. However, given the ease of exploitation (requires network access and knowledge of the API) and the potential for complete system compromise, this vulnerability is likely to receive a Critical severity rating once a CVSS score is assigned. A high CVSS score is anticipated.

Factors contributing to a potential high CVSS score:

• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N) – Assuming authentication bypass is possible or already achieved. Otherwise, Privileges Required would depend on the necessary permissions to call SetUserPassword().
• User Interaction: None (UI:N)
• Scope: Changed (S:C)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

Possible Impact

A successful exploit of CVE-2025-11786 can have severe consequences:

• Complete System Compromise: Attackers can gain full control of the PLC, allowing them to modify configurations, upload malicious code, and disrupt operations.
• Denial of Service (DoS): Attackers can cause the PLC to crash, halting critical industrial processes.
• Data Theft: Attackers can access sensitive data stored on the PLC or transmitted through the network.
• Lateral Movement: A compromised PLC can be used as a foothold to attack other systems within the ICS network.
• Physical Damage: In some scenarios, attackers can manipulate the PLC to cause physical damage to equipment or endanger human safety.

Mitigation and Patch Steps

Circutor has likely released a patch to address this vulnerability. It is strongly recommended to take the following steps:

1. Immediately Upgrade Firmware: Download and install the latest firmware version from the official Circutor website. Ensure the updated firmware version is confirmed to address CVE-2025-11786.
2. Network Segmentation: Isolate the PLC network from the broader corporate network to limit the potential for lateral movement in case of a breach.
3. Access Control: Implement strict access control policies to restrict access to the PLC to authorized personnel only.
4. Password Hardening: Enforce strong password policies and regularly review user accounts.
5. Intrusion Detection and Prevention Systems (IDS/IPS): Deploy IDS/IPS solutions to monitor network traffic for malicious activity and block suspicious connections.
6. Vulnerability Scanning: Regularly scan the PLC network for known vulnerabilities.