CVE-2025-11543

Executive Summary

CVE-2025-11543 identifies a critical security vulnerability in Sharp Display Solutions projectors. The flaw lies in the improper validation of integrity check values during firmware update processes. This allows an attacker with network access to the projector’s management interface to create and run unauthorized firmware, effectively gaining full control over the device. The vulnerability is classified under CWE-354 (Improper Validation of Integrity Check Value). As of this report, no official patch has been released, and no public proof-of-concept (PoC) code is available. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the potential impact on enterprise environments using these projectors for presentations or digital signage is significant.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a hardware/firmware-level issue in Sharp projectors. However, organizations should verify the integrity of firmware updates obtained from Sharp’s official channels and ensure that any third-party software used to manage these projectors is also secure.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder. Based on the description and CWE, a realistic assessment would be:

• Attack Vector (AV): Network (AV:N) – The attacker can exploit the vulnerability remotely.
• Attack Complexity (AC): Low (AC:L) – No special conditions are required.
• Privileges Required (PR): None (PR:N) – No authentication needed to trigger the flaw.
• User Interaction (UI): None (UI:N) – No user action required.
• Scope (S): Changed (S:C) – The vulnerable component impacts resources beyond its security scope.
• Confidentiality (C): High (C:H) – Full device compromise leads to data exposure.
• Integrity (I): High (I:H) – Attacker can modify firmware and device behavior.
• Availability (A): High (A:H) – Malicious firmware can render the device unusable.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Estimated Score: 10.0 (Critical)

Threat Level: Critical. The ability to run unauthorized firmware gives an attacker persistent, stealthy control over the projector, which could be used as a pivot point within a network or to exfiltrate sensitive presentation data.

Deep Dive & Mechanics

The vulnerability resides in the firmware update mechanism of Sharp projectors. Typically, firmware updates are digitally signed or include an integrity check value (e.g., checksum, hash) to ensure the update is authentic and untampered. In this case, the projector fails to properly validate this integrity check value. This means an attacker can craft a malicious firmware image with a spoofed or invalid integrity check value, and the projector will accept and execute it.

Attack Flow:

1. Reconnaissance: The attacker identifies Sharp projectors on the network, often via Shodan or network scanning (e.g., port 80/443 for web interface, or proprietary ports).
2. Access: The attacker gains access to the projector’s management interface, which may be unprotected or use default credentials.
3. Firmware Upload: The attacker uploads a malicious firmware image that bypasses integrity validation.
4. Execution: The projector reboots and runs the attacker’s firmware, giving the attacker full control over the device’s operating system and hardware.

Impact: The attacker can:

• Install persistent backdoors.
• Monitor or manipulate displayed content.
• Use the projector as a foothold for lateral movement.
• Disable the device for denial-of-service.

Vulnerable vs. Patched Code

No specific code snippets are available for this vulnerability. However, the general pattern is:

Vulnerable Code (Pseudocode):

if (firmware_update_received) {
    // Missing or weak integrity check
    apply_firmware(update_data);
}

Patched Code (Expected):

if (firmware_update_received) {
    if (verify_integrity_check(update_data) == VALID) {
        apply_firmware(update_data);
    } else {
        reject_update();
    }
}

The fix would involve implementing a robust integrity verification mechanism, such as cryptographic signature verification using a public key embedded in the projector’s firmware.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Target: Sharp projector (e.g., model XG-PH70X or similar) with default credentials.
• Attacker: Kali Linux machine on the same network.

Steps:

1. Discover the projector: Use nmap to scan for Sharp projectors.

   nmap -p 80,443,5000 --open 192.168.1.0/24
   

2. Access web interface: Navigate to the projector’s IP in a browser. Default credentials may be admin/admin.
3. Craft malicious firmware: Since no PoC exists, the attacker would need to reverse-engineer a legitimate firmware update to understand the format and integrity check mechanism. Tools like binwalk and firmware-mod-kit can help.
4. Upload firmware: Use the web interface’s firmware update page to upload the malicious image.
5. Verify compromise: After reboot, the attacker can connect to a reverse shell or backdoor embedded in the firmware.

Note: Without a public exploit, this is a theoretical exercise. The attacker must have significant firmware analysis skills.

Blue Team (Defensive)

Detection:

• Monitor network traffic for large file uploads to projector IPs on ports 80/443.
• Look for unusual outbound connections from projectors (e.g., to unknown IPs).
• Check for unexpected reboots or firmware version changes.

Prevention:

• Isolate projectors on a separate VLAN with strict firewall rules.
• Disable remote firmware update if not needed.
• Use strong, unique passwords for projector management interfaces.
• Regularly audit firmware versions and compare with official Sharp releases.

Indicators of Compromise (IOCs)

• Network:
  • Outbound connections from projector to unknown IPs on ports 80/443 or custom ports.
  • Large HTTP POST requests to /cgi-bin/firmware_update or similar endpoints.
• Host (Projector):
  • Unexpected firmware version not listed on Sharp’s support site.
  • Unusual processes running on the projector (if accessible via SSH).
  • Modified system files or binaries.
• Logs:
  • Web interface logs showing firmware uploads from unknown IPs.
  • System logs indicating unexpected reboots or firmware changes.

Detection Engineering

YARA Rule

rule Sharp_Projector_Malicious_Firmware {
    meta:
        description = "Detects malicious firmware images targeting Sharp projectors"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-11543"
    strings:
        $s1 = "Sharp" ascii wide nocase
        $s2 = "firmware" ascii wide nocase
        $s3 = "update" ascii wide nocase
        $s4 = { FF D8 FF E0 } // JPEG header (common in firmware images)
    condition:
        all of ($s1, $s2, $s3) and $s4
}

Sigma Rule

title: Sharp Projector Firmware Upload Detection
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP POST requests to Sharp projector firmware update endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem:
            - '/cgi-bin/firmware_update'
            - '/upload_firmware'
            - '/update'
    condition: selection
falsepositives:
    - Legitimate firmware updates from authorized administrators
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"Sharp Projector Firmware Upload Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/cgi-bin/firmware_update"; http_uri; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate projectors: Place them on a separate VLAN with strict access controls.
2. Disable remote firmware update: If not required, disable the feature in the projector’s settings.
3. Change default credentials: Use strong, unique passwords for all projector management interfaces.
4. Monitor network traffic: Look for unusual activity to/from projectors.

Long-Term Fix:

• Apply an official firmware patch from Sharp when released.
• Implement network segmentation and monitoring for all IoT/OT devices.
• Conduct regular security audits of firmware and device configurations.

Workaround:

• If firmware updates are necessary, download them from Sharp’s official website and verify their integrity using external tools (e.g., SHA-256 checksums) before uploading.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert