Hall said he informed Yahoo, WinZip and FBI about the issue.
Yahoo earlier today said their servers were compromised by the ShellShock vulnerability. But, Yahoo's Chief Information Security Officer Alex Stamos published a statement in Hacker News that the breach is not a result of 'Shell Shock'.
"Three of our Sports API servers had malicious code executed on them this weekend by attackers looking for vulnerable Shellshock servers." Stamos wrote.
"These attackers had mutated their exploit, [and] this mutation happened to exactly fit a command injection bug in a monitoring script our Sports team was using at that moment to parse and debug their web logs."
The company claimed hackers did not gain access to any user data and the affected servers are used to provide live streaming for its sports service that don't store user data.
In response, Hall said in his blog "The Yahoo! infiltration WAS from the 'Shellshock' vulnerability, and it did NOT originate on the sports servers / API’s".