1/5 Lawrence Abrams Malware now using NVIDIA's stolen code signing certificates bleepingcomputer.com/news/security/malware-now-using-nvidias-stolen-code-signing-certificates/ By Lawrence Abrams March 5, 2022 03:45 PM 4 Threat actors are using stolen NVIDIA code signing certificates to sign malware to appear trustworthy and allow malicious drivers to be loaded in Windows. This week, NVIDIA confirmed that they suffered a cyberattack that allowed threat actors to steal employee credentials and proprietary data. The extortion group, known as Lapsus$, states that they stole 1TB of data during the attack and began leaking the data online after NVIDIA refused to negotiate with them. https://www.bleepingcomputer.com/news/security/malware-now-using-nvidias-stolen-code-signing-certificates/ https://www.bleepingcomputer.com/author/lawrence-abrams/ 2/5 Lapsus$ messages about the NVIDIA attack The leak includes two stolen code-signing certificates used by NVIDIA developers to sign their drivers and executables. As part of the #NvidiaLeaks, two code signing certificates have been compromised. Although they have expired, Windows still allows them to be used for driver signing purposes. See the talk I gave at BH/DC for more context on leaked certificates: https://t.co/UWu3AzHc66 pic.twitter.com/gCrol0BxHd — Bill Demirkapi (@BillDemirkapi) March 3, 2022 A code-signing certificate allows developers to digitally sign executables and drivers so that Windows and end-users can verify the file's owner and whether they have been tampered with by a third party. To increase security in Windows, Microsoft also requires kernel-mode drivers to be code signed before the operating system will load them. NVIDIA certificates used to sign malware After Lapsus$ leaked NVIDIA's code-signing certificates, security researchers quickly found that the certificates were being used to sign malware and other tools used by threat actors. https://twitter.com/hashtag/NvidiaLeaks?src=hash&ref_src=twsrc%5Etfw https://t.co/UWu3AzHc66 https://t.co/gCrol0BxHd https://twitter.com/BillDemirkapi/status/1499437244830175236?ref_src=twsrc%5Etfw https://twitter.com/cyb3rops/status/1499514240008437762 3/5 According to samples uploaded to the VirusTotal malware scanning service, the stolen certificates were used to sign various malware and hacking tools, such as Cobalt Strike beacons, Mimikatz, backdoors, and remote access trojans. For example, one threat actor used the certificate to sign a Quasar remote access trojan [VirusTotal], while someone else used the certificate to sign a Windows driver [VirusTotal]. Quasar RAT signed by NVIDIA certificate Security researchers Kevin Beaumont and Will Dormann shared that the stolen certificates utilize the following serial numbers: 43BB437D609866286DD839E1D00309F5 14781bc862e8dc503a559346f5dcc518 Some of the files were likely uploaded to VirusTotal by security researchers but others appear to be used by threat actors for malware campaigns [1, 2]. https://www.virustotal.com/gui/file/065077fa74c211adf9563f00e57b5daf9594e72cea15b1c470d41b756c3b87e1 https://www.virustotal.com/gui/file/2f578cb0d97498b3482876c2f356035e3365e2c492e10513ff4e4159eebc44b8/detection https://twitter.com/GossiTheDog https://twitter.com/wdormann https://www.virustotal.com/gui/file/a0aa66f6639e2b54a908115571c85285598845d3e52888fe27c6b35f6900fe56/detection https://www.virustotal.com/gui/file/a7c3ce181e5c3956bb6b9b92e862b6fea6d6d3be1a38321ebb84428dde127677/relations 4/5 While both stolen NVIDIA certificates are expired, Windows will still allow a driver signed with the certificates to be loaded in the operating system. Therefore, using these stolen certificates, threat actors gain the advantage of making their programs look like legitimate NVIDIA programs and allowing malicious drivers to be loaded by Windows. Signed Quasar RAT sample To prevent known vulnerable drivers from being loaded in Windows, David Weston, director of enterprise and OS security at Microsoft, tweeted that admins can configure Windows Defender Application Control policies to control what NVIDIA drivers can be loaded. WDAC policies work on both 10-11 with no hardware requirements down to the home SKU despite some FUD misinformation i have seen so it should be your first choice. Create a policy with the Wizard and then add a deny rule or allow specific versions of Nvidia if you need — David Weston (DWIZZZLE) (@dwizzzleMSFT) March 3, 2022 However, using WDAC is not an easy task, especially for non-IT Windows users. https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/select-types-of-rules-to-create https://twitter.com/dwizzzleMSFT/status/1499527802382471188?ref_src=twsrc%5Etfw 5/5 Due to the potential for abuse, it is hoped that the stolen certificates will be added to Microsoft's certificate revocation list in the future to prevent malicious drivers from loading in Windows. However, doing so will cause legitimate NVIDIA drivers to be blocked as well, so we will likely not see this happening soon. Related Articles: Industrial Spy data extortion market gets into the ransomware game New RansomHouse group sets up extortion market, adds first victims NVIDIA fixes ten vulnerabilities in Windows GPU display drivers NVIDIA has open-sourced its Linux GPU kernel drivers NVIDIA fined for failure to disclose cryptomining sales boost Lawrence Abrams Lawrence Abrams is the owner and Editor in Chief of BleepingComputer.com. Lawrence's area of expertise includes Windows, malware removal, and computer forensics. Lawrence Abrams is a co-author of the Winternals Defragmentation, Recovery, and Administration Field Guide and the technical editor for Rootkits for Dummies. https://www.bleepingcomputer.com/news/security/industrial-spy-data-extortion-market-gets-into-the-ransomware-game/ https://www.bleepingcomputer.com/news/security/new-ransomhouse-group-sets-up-extortion-market-adds-first-victims/ https://www.bleepingcomputer.com/news/security/nvidia-fixes-ten-vulnerabilities-in-windows-gpu-display-drivers/ https://www.bleepingcomputer.com/news/linux/nvidia-has-open-sourced-its-linux-gpu-kernel-drivers/ https://www.bleepingcomputer.com/news/technology/nvidia-fined-for-failure-to-disclose-cryptomining-sales-boost/ https://www.bleepingcomputer.com/author/lawrence-abrams/