CVE-2022-36436: Twisted VNC Authentication Proxy authentication bypass

By Marios Levogiannis | Blog | No Comments

Introduction GRNET provides virtualization services on top of a custom virtualization infrastructure. In this context, we offer to our users optional VNC (Virtual Network Computing) access to their VMs. On the backend, the infrastructure utilizes OSU Open Source Lab’s Twisted VNC Authentication Proxy (also known as VNCAuthProxy) to dynamically allow multiple clients to connect to a VM’s VNC console using different passwords. During a periodic security audit of our infrastructure we discovered a new security vulnerability in the Twisted VNC Authentication Proxy. The vulnerability allows an attacker to bypass the proxy server’s authentication mechanism and connect to a VNC server…

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Reverse engineering Emotet – Our approach to protect GRNET against the trojan

By Dimitris Kolotouros and Marios Levogiannis | Blog | 15 Comments

Preamble In October 2020 we observed an outbreak of malicious e-mails reaching GRNET employees’ inboxes. Meanwhile, similar campaigns were also targeting several public and private sector organizations in Greece. After acquiring dozens of such e-mails, we started planning our defensive strategy. To do so, we started analyzing the malware that was attached to the emails and realized that were dealing with the infamous Emotet trojan. In this document, we describe the steps of our analysis including the reverse engineering process of the malware executables, how we overcame the binary obfuscation techniques it employed, and how we determined the malware’s internals….

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