Bekker's Blog

Blog archive

Report: 'Meltdown' Patch Did More Harm than Good for Windows 7

Patches that were released in January to protect Windows 7 from the Meltdown flaw may have opened an even worse can of worms for the OS, according to one security researcher.

Ulf Frisk, a security researcher who specializes in direct memory access (DMA) attacks, described the problem this week in a blog post called "Total Meltdown?"

The January patch was intended to address the Meltdown flaw in Intel, IBM POWER and ARM-based processors that emerged in January and theoretically allows a rogue process to read all memory on a system.

"[The patch] stopped Meltdown but opened up a vulnerability way worse...It allowed any process to read the complete memory contents at gigabytes per second, oh -- it was possible to write to arbitrary memory as well," wrote Frisk, who is the author of the PCILeech memory access attack toolkit, and who described himself in a DEFCON 24 presentation in 2016 as a penetration tester specializing in online banking security and working in Stockholm, Sweden.

[Click on image for larger view.] Using his PCILeech tool, researcher Ulf Frisk demonstrates the speed of memory dumping from Windows 7 with the January patches at 4GB/s (left). The dump speed is slightly slower when dumping the memory to disk (right). (Image source: Ulf Frisk)

"No fancy exploits were needed. Windows 7 already did the hard work of mapping in the required memory into every running process. Exploitation was just a matter of read and write to already mapped in-process virtual memory. No fancy APIs or syscalls required -- just standard read and write," Frisk said.

The flaw does not affect Windows 10 or Windows 8, according to Frisk.

The problem appears to have been introduced by the Windows 7 patches released in January, during the industrywide scramble to address the Meltdown and related Spectre flaws whose existence was revealed slightly ahead of schedule. Some of the first-generation patches caused reboot and slowdown issues, among other problems.

Frisk said the subsequent March patch for Windows 7 fixed the flaw, and he discovered the problem after the March patch was released.

Posted by Scott Bekker on March 28, 2018


Featured

  • Microsoft Appoints Althoff as New CEO for Commercial Business

    Microsoft CEO and chairman Satya Nadella on Wednesday announced the promotion of Judson Althoff to CEO of the company's commercial business, presenting the move as a response to the dramatic industrywide shifts caused by AI.

  • Broadcom Revamps VMware Partner Program Again

    Broadcom recently announced a significant update regarding its VMware Cloud Service Provider (VCSP) program, coinciding with the release of VMware Cloud Foundation (VCF) 9.0, a key component in Broadcom’s private cloud strategy.

  • Closeup of the new Copilot keyboard key

    Microsoft Updates Copilot To Add Context-Sensitive Agents to Teams, SharePoint

    Microsoft has rolled out a new public preview for collaborative "always on" agents in Microsoft 365 Copilot, bringing enhanced, context-aware tools into Teams channels, meetings, SharePoint sites, Planner workstreams and Viva Engage communities.

  • Windows 365 Cloud Apps Now Available for Public Preview

    Microsoft announced this week that Windows 365 Cloud Apps are now available for public preview. This aims to allow IT administrators to stream individual Windows applications from the cloud, removing the need to assign Cloud PCs to every user.