It has come to Block’s attention that the March 2018 release of Microsoft Security Rollups for Microsoft Operating Systems introduces a critical bug. The updates affected (KB4088875 and KB4088878) cause the first NIC of the computer to be re-detected as a new network device, thereby losing all networking configuration applied.

When applied to computers using DHCP, there appears to be no impact. However, when applied to computers with static network configuration, computers are reverted to default network configuration and become unavailable on the network, taking provided services down.

Microsoft has acknowledged the issue at this time, although there is no defined timeframe for resolution.

At this stage, Block recommends that customers carefully consider the risk to their environment posed by applying either of these patches. Should customers proceed with this installation, they should be prepared to do so on a case by case basis, correcting issues with the network configuration manually.

Should you have any queries at all, please don’t hesitate to contact our Security & Vulnerability Team