Critics fume after Github removes exploit code for Exchange vulnerabilities

Github has ignited a firestorm after the Microsoft-owned code-sharing repository removed a proof-of-concept exploit for critical vulnerabilities in Microsoft Exchange that have led to as many as 100,000 server infections in recent weeks.

ProxyLogon is the name that researchers have given both to the four Exchange vulnerabilities under attack in the wild and the code that exploits them. Researchers say that Hafnium, a state-sponsored hacking group based in China, started exploiting ProxyLogon in January, and within a few weeks, five other APTs—short for advanced persistent threat groups—followed suit. To date, no fewer than 10 APTs have used ProxyLogon to target servers around the world.

Microsoft issued emergency patches last week, but as of Tuesday, an estimated 125,000 Exchange servers had yet to install it, security firm Palo Alto Networks said. The FBI and the Cybersecurity and Infrastructure Security Agency have warned that ProxyLogon poses a serious threat to businesses, nonprofits, and government agencies that remain vulnerable.