Security experts from the Tripwire VERT security team have discovered 795,357 SonicWall VPN appliances that were exposed online that are vulnerable to the CVE-2020-5135 RCE flaw.
“A buffer overflow vulnerability in SonicOS allows a remote attacker to cause Denial of Service (DoS) and potentially execute arbitrary code by sending a malicious request to the firewall. This vulnerability affected SonicOS Gen 6 version 220.127.116.11, 18.104.22.168, 22.214.171.124, SonicOSv 6.5.4.v and Gen 7 version 126.96.36.199.” reads the advisory published by SonicWall.
The CVE-2020-5135 is a stack-based buffer overflow that affects the SonicWall Network Security Appliance (NSA). The vulnerability can be exploited by an unauthenticated HTTP request involving a custom protocol handler.