CVE-2024-20497: Cisco Expressway Edge Vulnerability Allows Remote Attackers to Masquerade as Another User

A recent security vulnerability with identifier CVE-2024-20497 has been discovered in Cisco Expressway Edge (Expressway-E), giving an authenticated remote attacker the ability to masquerade as another user on the affected system. This vulnerability exists because the system lacks proper authorization checks for Mobile and Remote Access (MRA) users. By running specific crafted commands, an attacker can intercept calls to a particular phone number or make phone calls that appear on the recipient's caller ID as though they are coming from a different phone number. This article will break down the details of this vulnerability, provide a code snippet to demonstrate the attack, and reference original sources on the issue.

Original References

1. Cisco Security Advisory
2. NIST National Vulnerability Database

Exploit Details

To exploit this vulnerability (CVE-2024-20497), an attacker must have access to the Mobile and Remote Access (MRA) feature on an affected Cisco Expressway-E system. By using a series of crafted commands, the attacker can perform unauthorized actions, such as intercepting or making phone calls under a different user.

Below is a simplified code snippet that demonstrates one possible way to exploit this vulnerability

# Attacker logs in as an MRA user
LOGIN('attacker_username', 'attacker_password')

# Attacker bypasses authorization check
BYPASS_AUTHORIZATION()

# Attacker masquerades as another user
MASQUERADE_AS_USER('target_user')

# Attacker intercepts a call
INTERCEPT_CALL('target_phone_number')

# Attacker makes a call
MAKE_CALL('target_phone_number', 'caller_id_number')

It is important to note that the provided code snippet is just a theoretical example to understand the vulnerability better, and actual exploitation details would vary based on the attacker's knowledge of the target system and the specific Expressway-E version.

A successful exploit of this vulnerability can have severe outcomes, such as

1. Compromising the privacy and security of a company's communication system by gaining unauthorized access to sensitive calls.
2. Impersonating legitimate users, causing reputational damage and leading to potential fraud or other attacks.
3. Causing unauthorized charges on corporate phone bills by making calls using another user's phone number.

Recommendations

Cisco has provided updated software versions for its Expressway-E products to address this vulnerability. Administrators of affected systems should immediately upgrade their software to the latest available version.

Additionally, organizations should enforce strict access controls to limit users that have access to Mobile and Remote Access (MRA) features, monitor their network activity for any signs of suspicious behavior, and educate employees on the importance of strong authentication practices.

Final Thoughts

CVE-2024-20497 is a critical vulnerability in Cisco Expressway Edge that could allow an authenticated, remote attacker to masquerade as another user by exploiting weak authorization checks for MRA users. While the detailed code snippet was provided for explanatory purposes only, businesses using affected systems should take the necessary precautions mentioned above to mitigate the risks posed by this vulnerability and ensure the security of their communication systems.

Timeline

Published on: 09/04/2024 17:15:13 UTC
Last modified on: 09/05/2024 12:53:21 UTC