The first Patch Tuesday security bulletin for 2021 from Microsoft includes fixes for one bug under active attack, possibly linked to the massive SolarWinds hacks.

Microsoft addressed 10 critical bugs, one under active exploit and another publicly known, in its January Patch Tuesday roundup of fixes. In total it patched 83 vulnerabilities.

The most serious bug is a flaw in Microsoft’s Defender anti-malware software that allows remote attackers to infect targeted systems with executable code. Security experts are warning that Windows users who have not connected to internet recently and received an auto-update, should patch now.

This bug in the Microsoft Malware Protection Engine may already be patched on your system as the engine auto-updates as needed. However, if your systems are not connected to the internet, you’ll need to manually apply the patch.

Researchers believe the vulnerability, tracked as CVE-2021-1647, has been exploited for the past three months and was leveraged by hackers as part of the massive SolarWinds attack. Last month, Microsoft said state-sponsored hackers had compromised its internal network and leveraged additional Microsoft products to conduct further attacks.

Affected versions of Microsoft Malware Protection Engine range from 1.1.17600.5 to 1.1.17700.4 running on Windows 10, Windows 7 and 2004 Windows Server, according to the security bulletin.

Publicly Known Bug Fixed Twice
Microsoft patched a second vulnerability, that researchers believe was also being exploited in the wild, tracked as CVE-2021-1648. The flaw is classified as an elevation-of-privilege bug and impacts the Windows print driver process SPLWOW64.exe.

The bug first discovered by Google and patched. But ZDI believes that patch was insufficient and opened the door to further attacks. Childs said that ZDI re-discovered the flaw a second time, which Microsoft is patched again Tuesday.

8 critical bug included a remote code-execution bug in Microsoft’s Edge web browser. The vulnerability (CVE-2021-1705) is memory-related and tied to a the way the browser improperly access objects in memory.

Five January Patch Tuesday flaws (CVE-2021-1658, CVE-2021-1660, CVE-2021-1666, CVE-2021-1667 and CVE-2021-1673) were each remote procedure call bugs.

Additional critical bugs were tied to Windows Graphics Device Interface (CVE-2021-1665), HEVC Video Extensions (CVE-2020-1643), and the Microsoft DTV-DVD Video Decoder (CVE-2020-1668).

With the SolarWinds breach still fresh from December and the scope of impact growing by the day, there’s a reaffirmed urgency for organizations to implement best practices for even the most basic security habits,