CVE-2024-7011

Executive Summary

CVE-2024-7011 is a denial-of-service (DoS) vulnerability affecting a wide range of Sharp NEC projector models. The flaw resides in the SNMP service, allowing an unauthenticated attacker to crash the service or render the device unresponsive by sending specially crafted SNMP requests. Given the CVSS score of 0.0 (likely unassigned or placeholder), the actual severity may be higher in operational contexts where projectors are critical for presentations, digital signage, or command-and-control displays. No public proof-of-concept (PoC) or patch is currently available, but the vulnerability is exploitable over the network.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (placeholder; likely unassigned)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: None (I:N)
• Availability Impact: High (A:H)
• Threat Level: Medium (due to DoS impact and lack of patch)

Deep Dive & Mechanics

The vulnerability is triggered via the SNMP service (UDP port 161) running on the affected projector models. SNMP is used for remote monitoring and management. The flaw likely involves improper handling of malformed SNMP packets, such as oversized community strings, invalid OIDs, or malformed Get/Set requests. When the projector receives a crafted packet, it may enter an infinite loop, consume excessive memory, or crash the SNMP daemon, leading to a denial-of-service condition. The device may require a physical power cycle to recover.

Vulnerable vs. Patched Code

No patch is available. The vulnerable code is likely in the SNMP agent implementation (e.g., net-snmp or proprietary stack). Without a patch, the comparison is theoretical. The vulnerable code may lack input validation on SNMP packet fields, while a patched version would include bounds checking and proper error handling.

Exploitation & Lab Setup

Red Team

1. Reconnaissance: Scan for SNMP services on UDP port 161 using nmap -sU -p 161 <target>.
2. Craft Malformed SNMP Packet: Use a tool like scapy or snmpset with invalid community strings or OIDs.

   from scapy.all import *
   # Example: Send a malformed SNMP packet with oversized community string
   packet = IP(dst="192.168.1.100")/UDP(sport=12345, dport=161)/SNMP(community="A"*1024, version=1, PDU=SNMPget(request_id=1, varbindlist=[SNMPvarbind(oid=ASN1_OID("1.3.6.1.2.1.1.1.0"))]))
   send(packet)
   

3. Trigger DoS: Send multiple malformed packets to overwhelm the SNMP service.
4. Verify: Check if the projector becomes unresponsive to SNMP queries or network pings.

Blue Team

1. Monitor SNMP Traffic: Use tcpdump or Wireshark to capture SNMP packets on UDP port 161.
2. Detect Anomalies: Look for oversized community strings, malformed OIDs, or high frequency of SNMP requests.
3. Network Segmentation: Restrict SNMP access to trusted management IPs only.
4. Disable SNMP: If not required, disable SNMP on projectors via web interface or CLI.
5. Incident Response: If DoS occurs, power cycle the projector and review logs.

Indicators of Compromise (IOCs)

• Network: UDP packets to port 161 with community strings > 255 characters or malformed ASN.1 encoding.
• Logs: SNMP agent crash logs or repeated "SNMP request failed" messages.
• Behavior: Projector becomes unresponsive to SNMP queries, web interface, or remote control.

Detection Engineering

YARA Rule

rule CVE_2024_7011_SNMP_DoS {
   meta:
      description = "Detects malformed SNMP packets targeting Sharp NEC projectors"
      author = "Valters IT"
      date = "2025-04-10"
      reference = "CVE-2024-7011"
   strings:
      $snmp_header = { 30 ?? 02 01 00 04 ?? }
      $long_community = /04 [\x80-\xff] [\x01-\xff]{256,}/
   condition:
      $snmp_header and $long_community
}

Sigma Rule

title: CVE-2024-7011 SNMP DoS Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects malformed SNMP packets targeting Sharp NEC projectors
author: Valters IT
logsource:
   category: network
   product: suricata
detection:
   selection:
      dest_port: 161
      protocol: udp
      payload|contains: "04" # SNMP community string length field
      payload|length: > 512
   condition: selection
falsepositives:
   - Legitimate SNMP management with large community strings (unlikely)
level: high

Suricata Rule

alert udp $EXTERNAL_NET any -> $HOME_NET 161 (msg:"CVE-2024-7011 SNMP DoS Attempt"; content:"|04|"; offset:0; depth:2; byte_test:1,>,255,2; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Disable SNMP on all affected projector models if not required for management.
• Network: Restrict SNMP access to trusted IPs using firewall rules.
• Monitor: Implement detection rules (YARA, Sigma, Suricata) to alert on malformed SNMP traffic.
• Patch: Await official firmware update from Sharp NEC. Contact vendor support for status.
• Workaround: Use alternative management protocols (e.g., HTTP/HTTPS) if available.

Valters IT
DevSecOps & Cyber Threat Intelligence