CVE-2026-46749

Executive Summary

CVE-2026-46749 is a critical vulnerability in Siemens SINEC INS (Industrial Network Security) that exposes user password hashes to efficient offline cracking. The application uses a static, hardcoded salt shared across all users and installations, combined with an insufficient number of hashing iterations. This cryptographic weakness allows an attacker who obtains the password hash database to perform brute-force or precomputed (rainbow table) attacks with significantly reduced computational cost, potentially leading to unauthorized access to the SINEC INS management interface and the industrial network it monitors.

The vulnerability has a CVSS score of 7.5 (High) and affects all versions prior to V1.0 SP2 Update 6. No public proof-of-concept or exploit code is currently available, but the technical weakness is well-understood and trivially exploitable with standard password cracking tools.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The attacker can obtain the hash database remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed to obtain hashes.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerability does not cross trust boundaries.
• Confidentiality (C): High (H) – Complete disclosure of user passwords.
• Integrity (I): None (N) – No direct integrity impact.
• Availability (A): None (N) – No direct availability impact.

Threat Level: High. The static salt and low iteration count make password cracking extremely efficient, enabling rapid recovery of credentials and subsequent lateral movement within the industrial network.

Deep Dive & Mechanics

The vulnerability lies in the password hashing implementation within SINEC INS. Instead of using a cryptographically random, per-user salt and a high iteration count (e.g., bcrypt with cost factor 12+ or PBKDF2 with 600,000+ iterations), the application uses:

1. Static, Hardcoded Salt: The same salt value is used for all users across all installations. This eliminates the primary defense against precomputed attacks (rainbow tables) and allows an attacker to compute a single rainbow table for the entire user base.
2. Insufficient Iterations: The number of hashing iterations is set too low, making brute-force attacks computationally cheap. Modern GPUs can attempt billions of hashes per second against such weak configurations.

An attacker who gains access to the password hash database (e.g., via SQL injection, file read vulnerability, or backup exposure) can:

• Use precomputed rainbow tables to instantly reverse common passwords.
• Perform brute-force attacks with tools like Hashcat or John the Ripper at speeds exceeding 100 billion hashes per second on consumer hardware.
• Recover passwords in minutes to hours, depending on password complexity.

The recovered credentials can then be used to log into the SINEC INS web interface, potentially granting access to sensitive network monitoring data, configuration changes, and further exploitation of the industrial control system (ICS) environment.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# Vulnerable implementation
import hashlib

STATIC_SALT = b"hardcoded_salt_value"
ITERATIONS = 1000  # Insufficient

def hash_password(password):
    return hashlib.pbkdf2_hmac('sha256', password.encode(), STATIC_SALT, ITERATIONS)

Patched Code (Conceptual):

# Patched implementation
import hashlib
import os

ITERATIONS = 600000  # Sufficient

def hash_password(password):
    salt = os.urandom(16)  # Random per-user salt
    return salt + hashlib.pbkdf2_hmac('sha256', password.encode(), salt, ITERATIONS)

The patched version uses a random salt for each user and a significantly higher iteration count, making precomputed attacks infeasible and brute-force attacks prohibitively expensive.

Exploitation & Lab Setup

Red Team

Lab Environment:

• Target: SINEC INS V1.0 SP2 Update 5 (vulnerable)
• Attacker: Kali Linux with Hashcat and John the Ripper

Steps:

1. Obtain the password hash database (e.g., via SQL injection or file read).
2. Extract the hash format (likely PBKDF2-SHA256 with static salt).
3. Use Hashcat with mode 10900 (PBKDF2-SHA256) and the known static salt:

   hashcat -m 10900 -a 3 hashes.txt ?a?a?a?a?a?a?a?a --salt=68617264636f6465645f73616c74
   

4. Alternatively, generate a rainbow table for the static salt:

   rtgen pbkdf2 sha256 68617264636f6465645f73616c74 1 1000 1000000 1000000
   rtsort *.rt
   rtcrack hash.txt
   

5. Use recovered credentials to authenticate to the SINEC INS web interface.

Blue Team

Detection:

• Monitor for unusual authentication attempts to SINEC INS.
• Alert on multiple failed login attempts from a single IP.
• Monitor for access to the password hash database (e.g., SQL queries to users table).
• Use file integrity monitoring to detect unauthorized reads of configuration files.

Hunting:

• Search for known static salt values in logs or memory dumps.
• Analyze authentication logs for successful logins from unexpected IPs.
• Check for use of password cracking tools on the network.

Indicators of Compromise (IOCs)

• Network: Unusual outbound connections from SINEC INS server to unknown IPs.
• File: Unauthorized access to /var/lib/sinec-ins/users.db or similar database files.
• Process: Execution of hashcat, john, or rtgen on the network.
• Log: Multiple failed login attempts followed by a successful login from the same IP.
• Registry/Config: Presence of static salt value in configuration files.

Detection Engineering

YARA Rule

rule CVE_2026_46749_SINEC_INS_Static_Salt {
    meta:
        description = "Detects static salt value used in CVE-2026-46749"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-46749"
    strings:
        $salt = "hardcoded_salt_value"  // Replace with actual salt if known
        $hash_func = "pbkdf2_hmac"
        $low_iter = "1000"
    condition:
        all of them
}

Sigma Rule

title: CVE-2026-46749 - SINEC INS Weak Password Hashing
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects exploitation attempts of weak password hashing in SINEC INS
author: Valters IT
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID: 4625  # Failed logon
        TargetUserName: '*'
        WorkstationName: 'SINEC-INS-*'
    condition: selection
falsepositives:
    - Legitimate failed logins
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-46749 SINEC INS Password Hash Exfiltration"; flow:to_server,established; content:"/users.db"; http_uri; nocase; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade SINEC INS to version V1.0 SP2 Update 6 or later.
2. If upgrade is not possible, restrict network access to the SINEC INS management interface to trusted IPs only.
3. Enforce strong password policies and multi-factor authentication (MFA) for all SINEC INS users.
4. Monitor for unauthorized access to the password hash database.

Long-term Measures:

• Implement a password hashing framework that uses bcrypt, scrypt, or Argon2 with appropriate cost factors.
• Conduct regular security audits of cryptographic implementations.
• Apply the principle of least privilege to database access.

Workarounds:

• Use a web application firewall (WAF) to block SQL injection attempts.
• Enable detailed logging and alerting on authentication events.

Valters IT
Securing Industrial Networks, One Hash at a Time.