CVE-2026-4670

Executive Summary

CVE-2026-4670 is a critical authentication bypass vulnerability in Progress Software MOVEit Automation, a managed file transfer (MFT) solution. The flaw allows an unauthenticated attacker to bypass primary authentication mechanisms, potentially gaining full administrative access to the application. With a CVSS score of 9.8, this vulnerability poses a severe risk to organizations using affected versions, enabling data exfiltration, lateral movement, and complete compromise of the MOVEit environment. No public proof-of-concept (PoC) or patch is currently available, but the vulnerability is actively being monitored by threat intelligence sources.

Supply Chain & Package Security

MOVEit Automation is a proprietary software package distributed by Progress Software. As a closed-source product, there are no open-source package registries (NPM, PyPI, Go, Ruby) involved. However, the vulnerability impacts the supply chain of organizations that rely on MOVEit for secure file transfers, potentially exposing sensitive data and credentials.

CVSS Breakdown & Threat Level

• CVSS Score: 9.8 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Vulnerability affects only the vulnerable component.
• Confidentiality Impact: High (C:H) – Full data access.
• Integrity Impact: High (I:H) – Full data modification.
• Availability Impact: High (A:H) – Potential denial of service or system takeover.

Threat Level: Critical. Immediate action required. The vulnerability is remotely exploitable without authentication, making it a prime target for ransomware groups and APTs.

Deep Dive & Mechanics

The vulnerability resides in the authentication module of MOVEit Automation. The software uses a primary authentication mechanism (e.g., username/password or certificate-based) to verify user identity. Due to a flaw in the authentication bypass logic, an attacker can craft a specially crafted request that bypasses this check, granting unauthorized access.

Root Cause: The authentication bypass is likely due to improper validation of authentication tokens or session identifiers. The software may accept a null or malformed token as valid, or fail to enforce authentication checks on certain API endpoints.

Attack Vector: An attacker sends a crafted HTTP request to the MOVEit Automation web interface or API, exploiting the bypass to gain administrative privileges. This could be achieved by manipulating headers, cookies, or request parameters.

Impact: Once authenticated, an attacker can:

• Access and exfiltrate all files stored in MOVEit Automation.
• Modify or delete files and configurations.
• Create new user accounts with elevated privileges.
• Use the MOVEit server as a pivot point for lateral movement within the network.

Vulnerable vs. Patched Code

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

Vulnerable Code (Pseudocode):

def authenticate(request):
    token = request.headers.get('Authorization')
    if token is None or token == 'Bearer null':
        # Bypass: treat null token as valid
        return True
    # Validate token...

Patched Code (Hypothetical):

def authenticate(request):
    token = request.headers.get('Authorization')
    if token is None or not token.startswith('Bearer '):
        return False
    token_value = token.split(' ')[1]
    if token_value == 'null' or token_value == '':
        return False
    # Validate token...

The patched version explicitly rejects null or empty tokens, preventing the bypass.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A vulnerable MOVEit Automation instance (version < 2025.0.9, < 2024.1.8, or < 2024.0.0).
• Network access to the MOVEit web interface (typically port 443 or 80).

Exploitation Steps:

1. Identify the target MOVEit Automation server.
2. Send a crafted HTTP request to the authentication endpoint with a null or malformed token.
3. If successful, the server returns a session cookie or token granting administrative access.
4. Use the obtained session to access sensitive files and perform administrative actions.

Example Request (cURL):

curl -X POST https://target.moveit.local/api/v1/authenticate \
  -H "Authorization: Bearer null" \
  -H "Content-Type: application/json" \
  -d '{"username": "admin", "password": "ignored"}'

Note: No public exploit code is available. The above is a conceptual example.

Blue Team (Defensive)

Detection:

• Monitor for HTTP requests with unusual or null Authorization headers.
• Look for repeated authentication failures followed by sudden success.
• Alert on access to administrative endpoints from unexpected IPs.

Honeypot:

• Deploy a decoy MOVEit Automation instance to capture attacker behavior.
• Log all authentication attempts and analyze for bypass patterns.

Containment:

• Immediately isolate affected MOVEit servers from the network.
• Review logs for signs of unauthorized access.
• Rotate all credentials and API keys used by MOVEit.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests with Authorization: Bearer null or Authorization: Bearer undefined.
  • Unusual POST requests to /api/v1/authenticate or similar endpoints.
  • Connections from IP addresses not in the organization's allowlist.

• File IOCs:

  • New user accounts created in MOVEit Automation without proper authorization.
  • Unusual file access patterns (e.g., bulk downloads of sensitive files).

• System IOCs:

  • Unexpected changes to MOVEit configuration files.
  • Presence of unknown scripts or binaries in the MOVEit installation directory.

Detection Engineering

YARA Rule

rule CVE_2026_4670_AuthBypass {
    meta:
        description = "Detects authentication bypass attempts for CVE-2026-4670"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-4670"
    strings:
        $auth_bypass = "Bearer null" ascii wide nocase
        $auth_bypass2 = "Bearer undefined" ascii wide nocase
        $auth_bypass3 = "Authorization: null" ascii wide nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2026-4670 MOVEit Automation Authentication Bypass
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests with null or malformed Authorization headers targeting MOVEit Automation
author: Valters IT
date: 2026/01/01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-4670
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/api/v1/authenticate'
        cs-headers|contains: 'Authorization: Bearer null'
    condition: selection
falsepositives:
    - Legitimate testing
level: critical

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2026-4670 MOVEit Automation Authentication Bypass Attempt";
    flow:to_server;
    content:"POST"; http_method;
    content:"/api/v1/authenticate"; http_uri;
    content:"Authorization"; http_header;
    content:"Bearer null"; http_header;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected MOVEit Automation servers from the network.
2. Monitor logs for signs of exploitation.
3. Apply any available patches from Progress Software as soon as they are released.
4. Restrict network access to MOVEit servers using firewalls and VPNs.

Long-term Mitigations:

• Implement multi-factor authentication (MFA) for all MOVEit accounts.
• Use a web application firewall (WAF) to block suspicious requests.
• Regularly audit user accounts and permissions.
• Keep MOVEit Automation updated to the latest version.

Workarounds (if patch is unavailable):

• Disable the MOVEit Automation web interface if not required.
• Use network segmentation to limit access to trusted IPs only.
• Enable detailed logging and alerting for authentication events.

Valters IT
Securing Digital Frontiers

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