Outbreak Alert: CVE-2021-35394: OBA Realtek SDK UDPServer RCE

[sbhamidipati]

Description	This article describes the assessment of unauthenticated Remote Code Execution vulnerability in Realtek SDK UDP server with FortiDAST. In CVE-2021-35394, the UDPServer tool on Realtek SDK based devices contains an arbitrary command injection vulnerability. The diagnostic tool, 'MP Daemon' that is compiled as UDP Server binary is affected by multiple memory corruption vulnerabilities and an arbitrary command injection vulnerability which can be exploited by remote attackers.
Scope	FortiDAST Scripting Engine updated in version 23.3.a
Solution	Detection against that vulnerability is empowered by the FortiDAST Scripting Engine (FSE). This technology enables FortiDAST to assess remotely with a high level of confidence if an asset is vulnerable to a specific vulnerability by testing the disarmed exploit against the asset itself. To configure the scan, it will be necessary to enable the FSE group signature 'realtek' which will select the underlying script: ‘CVE-2021-35394 Realtek SDK UDPServer RCE vulnerability.’ For reference, a step-by-step guide on how to configure FortiDAST to trigger FSE can be found on Fortinet’s blog: https://www.fortinet.com/blog/business-and-technology/fortipentest-exploit-engine-a-new-security-ars...