Junglewise Threat Intelligence

CVE-2024-3596: RADIUS Protocol MD5 collision forgery attack (Blast-RADIUS)

CVE-2024-3596 · Severity: critical · CVSS 9 · Published 2024-07-09

Technologies: SonicWall SonicOS. Vendors: Siemens, SonicWall, Broadcom.

Executive brief

A fundamental flaw has been identified in the RADIUS protocol, a widely used standard for authenticating users on corporate networks, VPNs, and networking equipment. An attacker positioned on the network between a device and the authentication server can intercept and modify traffic to grant themselves unauthorized access. This could allow an attacker to bypass security checks, including multi-factor authentication, and gain full access to sensitive network resources without needing valid credentials.

Technical details

The RADIUS protocol (RFC 2865) is susceptible to a chosen-prefix collision attack against the MD5-based Response Authenticator signature. An on-path attacker (Man-in-the-Middle) can intercept an Access-Request and modify the server's response (e.g., changing an Access-Reject to an Access-Accept) by manipulating the MD5 hash. This is possible because the protocol lacks mandatory integrity checks for the entire packet in many configurations. The attack, known as 'Blast-RADIUS', allows for the injection of arbitrary attributes and can bypass Multi-Factor Authentication (MFA) if it relies on Access-Challenge packets. Mitigation requires enforcing the 'Message-Authenticator' attribute or migrating to RADIUS over TLS (RadSec) or DTLS.

Affected products

  • FreeRADIUS FreeRADIUS < 3.0.27
  • IETF RADIUS Protocol (RFC 2865) All versions using MD5 Response Authenticator without Message-Authenticator attribute
  • Siemens RUGGEDCOM ROS < V4.3.11
  • Siemens RUGGEDCOM CROSSBOW < V5.6
  • Broadcom Fabric Operating System
  • SonicWall SonicOS

Timeline

  • 2024-07-09: disclosed: Public disclosure of Blast-RADIUS attack
  • 2024-07-09: advisory: Initial NVD and vendor advisories published

References

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