Tripwire VERT has identified a stack-based buffer overflow in SonicWall Network Security Appliance (NSA). The flaw can be triggered by an unauthenticated HTTP request involving a custom protocol handler. The vulnerability exists within the HTTP/HTTPS service used for product management as well as SSL VPN remote access.
Exposure and Impact
An unskilled attacker can use this flaw to cause a persistent denial of service condition. Tripwire VERT has also confirmed the ability to divert execution flow through stack corruption indicating that a code execution exploit is likely feasible. This flaw exists pre-authentication and within a component (SSLVPN) which is typically exposed to the public Internet. As of the date of discovery, a Shodan search for the affected HTTP server banner indicated 795,357 hosts.
SonicWall has indicated that the following versions are vulnerable:
- SonicOS 184.108.40.206-79n and earlier
- SonicOS 220.127.116.11-4n and earlier
- SonicOS 18.104.22.168-93o and earlier
- SonicOSv 22.214.171.124-44v-21-794 and earlier
- SonicOS 126.96.36.199-1
Remediation & Mitigation
SonicWall has released updates to remediate this flaw. SSL VPN portals may be disconnected from the Internet as a temporary mitigation before the patch is applied.
SonicWall has indicated that the following versions include a fix for this issue:
- SonicOS 188.8.131.52-83n
- SonicOS 184.108.40.206-1n
- SonicOS 220.127.116.11-94o
- SonicOS 6.5.4.v-21s-987
- Gen 7 18.104.22.168-2 and onwards
Tripwire IP360 starting with ASPL-909 contains remote heuristic detection of the vulnerable service.
More information about detecting possible attacks will be shared as needed after more system owners have had an opportunity to patch.
*** This is a Security Bloggers Network syndicated blog from The State of Security authored by Craig Young. Read the original post at: https://www.tripwire.com/state-of-security/vert/sonicwall-vpn-portal-critical-flaw-cve-2020-5135/