CVE-2024-25655

Executive Summary

CVE-2024-25655 exposes a critical security flaw in AVSystem Unified Management Platform (UMP) version 23.07.0.16567~LTS. The vulnerability stems from insecure storage of LDAP passwords within the authentication module. Any authenticated member with read access to the application database can decrypt the LDAP passwords of users who successfully authenticate via LDAP. This allows for lateral movement and privilege escalation within the network, as LDAP credentials often grant access to broader directory services and associated systems. The vulnerability is currently unpatched, and no public exploit code is available.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or uncalculated value. Based on the vulnerability description, a reasonable assessment would be:

• Attack Vector (AV): Network (N) – The attacker needs network access to the application database.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker must be an authenticated member with read access to the database.
• User Interaction (UI): None (N) – No user interaction is required.
• Scope (S): Changed (C) – The compromised LDAP credentials can be used to access other systems.
• Confidentiality (C): High (H) – LDAP passwords are fully exposed.
• Integrity (I): High (H) – LDAP credentials can be used to modify directory data.
• Availability (A): None (N) – The vulnerability does not directly impact availability.

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

Threat Level: High. The ability to decrypt LDAP passwords from the database provides a direct path to compromising the entire directory service and any systems relying on it.

Deep Dive & Mechanics

The vulnerability lies in the authentication functionality of AVSystem UMP. When a user authenticates via LDAP, the system stores the LDAP password in an insecure manner within the application database. The exact mechanism is not publicly detailed, but it likely involves:

1. Weak Encryption/Encoding: The password may be stored using a reversible encryption algorithm (e.g., AES with a hardcoded key, or a simple base64 encoding) instead of a one-way hash.
2. Insecure Key Management: The decryption key may be stored in the application configuration, source code, or a location accessible to database readers.
3. Database Access: An attacker with read access to the database (e.g., through SQL injection, compromised database credentials, or a malicious insider) can retrieve the encrypted password field.
4. Decryption: Using the known or discoverable decryption method, the attacker can recover the plaintext LDAP password.

This allows the attacker to then authenticate to the LDAP server as the compromised user, gaining access to all resources and permissions associated with that LDAP account.

Vulnerable vs. Patched Code

Since no patch is available, a direct code comparison is not possible. However, the vulnerable code likely resembles:

# Vulnerable approach (pseudocode)
def store_ldap_password(user, password):
    encrypted_password = base64.b64encode(password.encode())
    db.execute("UPDATE users SET ldap_password = ? WHERE id = ?", (encrypted_password, user.id))

A patched version would use a one-way hash with a salt:

# Patched approach (pseudocode)
import hashlib, os
def store_ldap_password(user, password):
    salt = os.urandom(32)
    hashed_password = hashlib.pbkdf2_hmac('sha256', password.encode(), salt, 100000)
    db.execute("UPDATE users SET ldap_password_hash = ?, ldap_password_salt = ? WHERE id = ?", (hashed_password, salt, user.id))

Exploitation & Lab Setup

Red Team

Objective: Extract and decrypt LDAP passwords from the AVSystem UMP database.

Prerequisites:

• Access to the AVSystem UMP application database (e.g., via SQL injection, compromised DB credentials, or insider access).
• Knowledge of the encryption/decryption method used (e.g., hardcoded key in application code).

Steps:

1. Identify Database Location: Determine the database type (e.g., PostgreSQL, MySQL) and connection details.
2. Extract Encrypted Passwords: Query the users table for the ldap_password field.

   SELECT username, ldap_password FROM users WHERE ldap_password IS NOT NULL;
   

3. Decrypt Passwords: Use the known decryption method. For example, if AES with a hardcoded key is used:

   from Crypto.Cipher import AES
   import base64
   key = b'hardcoded_key_32_bytes_long'
   cipher = AES.new(key, AES.MODE_ECB)
   for encrypted_password in extracted_passwords:
       decrypted = cipher.decrypt(base64.b64decode(encrypted_password))
       print(decrypted.decode().rstrip())
   

4. Authenticate to LDAP: Use the recovered credentials to authenticate to the LDAP server and access directory resources.

Blue Team

Objective: Detect and prevent exploitation of CVE-2024-25655.

Detection:

• Monitor database queries for unusual access to the users table, especially the ldap_password field.
• Alert on any decryption attempts or use of hardcoded keys in application logs.
• Monitor for successful LDAP authentication from unexpected sources or at unusual times.

Mitigation:

• Restrict database access to only necessary services and users.
• Implement database activity monitoring (DAM) solutions.
• Apply the principle of least privilege to database accounts.
• If possible, disable LDAP password storage or use a secure, one-way hashing mechanism.
• Monitor for any patches from AVSystem and apply them immediately.

Indicators of Compromise (IOCs)

• Network: Unusual LDAP authentication attempts from IP addresses not normally associated with the UMP server.
• Database: Queries selecting the ldap_password column from the users table.
• Application Logs: Entries showing decryption of stored passwords or use of hardcoded cryptographic keys.
• File System: Presence of scripts or tools designed to decrypt LDAP passwords (e.g., Python scripts using Crypto.Cipher).

Detection Engineering

YARA Rule

rule CVE_2024_25655_LDAP_Password_Decrypt {
    meta:
        description = "Detects scripts attempting to decrypt LDAP passwords stored in AVSystem UMP"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-25655"
    strings:
        $aes_import = "from Crypto.Cipher import AES" ascii wide nocase
        $base64_import = "import base64" ascii wide nocase
        $ldap_password_field = "ldap_password" ascii wide nocase
        $decrypt_loop = "decrypt" ascii wide nocase
    condition:
        all of ($aes_import, $base64_import, $ldap_password_field) or
        ($decrypt_loop and $ldap_password_field)
}

Sigma Rule

title: CVE-2024-25655 - LDAP Password Extraction from AVSystem UMP Database
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL queries targeting the ldap_password column in AVSystem UMP database
author: Valters IT
date: 2024/01/01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-25655
logsource:
    category: database
    product: postgresql
    service: postgres
detection:
    selection:
        query|contains: 'ldap_password'
    condition: selection
falsepositives:
    - Legitimate database administration
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 389 (msg:"CVE-2024-25655 - Potential LDAP Credential Reuse"; flow:to_server,established; content:"|30 0c 02 01 01 60 07 02 01 03 04 00 80 00|"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict Database Access: Limit read access to the application database to only essential services and personnel.
2. Change LDAP Passwords: Force all users who authenticate via LDAP to change their passwords immediately.
3. Monitor for Unauthorized Access: Review database logs for any suspicious queries targeting the ldap_password column.
4. Implement Network Segmentation: Isolate the AVSystem UMP server and its database from the broader network.

Long-Term Fixes:

1. Apply Patch: Monitor AVSystem for a security patch and apply it as soon as it becomes available.
2. Harden Password Storage: If possible, modify the application to use a one-way hash (e.g., bcrypt, PBKDF2) for storing LDAP passwords.
3. Conduct Security Audit: Perform a thorough security audit of the AVSystem UMP deployment to identify other potential vulnerabilities.
4. Implement Database Activity Monitoring (DAM): Deploy a DAM solution to detect and alert on suspicious database queries.

Valters IT