Microsoft fixed a number of issues in its operating systems, which also included a patch for a bug in Silverlight, the company's application platform equivalent to Flash.
According to Kaspersky, two of the company's security researchers, Costin Raiu and Anton Ivanov, uncovered a Silverlight zero-day bug in 400GB of data dumped online after the breach in June 2015.
They were initially suspected by an email included in Hacking Team's data, which was later published in an ArsTechnica article.
Hacker tried to sell Silverlight to Hacking Team
The email was from a Russian hacker named Vitaliy Toropov, writing to Hacking Team, asking if they were interested in buying zero-days in applications like Flash, Silverlight, Java, or Safari.
According to the published emails, Toropov revealed that he had in his possession a 2.5-year-old Silverlight zero-day, which had the potential to remain secret for a few more years.
Kaspersky researchers were soon able to find that the Silverlight exploit code belonged to Toropov on the Packet Storm Security portal.
The zero-day bug was used in the November live attacks
According to Kaspersky, the file that triggered the security warning was created on July 21, 2015, just a few weeks after the Hacking Team attack.
When exploited through a Web browser, the bug allows an attacker to gain the same privileges as the user on the infected computer. While not a dangerous threat on its own, the bug can be linked to other zero-days and used to carry out more dangerous attacks.
While researchers can't be sure that this is the exact zero-day that Toropov tried to sell to Hacking Team, they do know that it is Toropov's work, and that it has now been patched, thanks to their efforts and those of Microsoft's security staff.
