Bootkits: Past, Present & Future - Virus Bulletin
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The document discusses the evolution of bootkits, comparing legacy BIOS and UEFI boot environments, and detailing various malwares that exploit these technologies. It highlights bootkit implementation strategies, attacks against secure boot, and forensic tools like hiddenfsreader. Furthermore, it addresses concerns around secure boot and the evolving threat landscape, illustrating techniques used by modern bootkits and the vulnerabilities associated with firmware and BIOS protections.
![Gapz BPB Layout
struct BIOS_PARAMETER_BLOCK
{
WORD BytesPerSector;
BYTE SecPerCluster;
WORD ReservedSectors;
BYTE Reserved[5];
BYTE MediaDescriptorID;
WORD Reserved2;
WORD SectorsPerTrack;
WORD NumberOfHeads;
DWORD HiddenSectors;
DWORD Reserved3[2];
LONGLONG TotalSectors;
LONGLONG StartingCluster;
LONGLONG MFTMirrStartingCluster;
DWORD ClustersPerMFTRecord;
DWORD ClustersPerIndexBuffer;
LONGLONG VolumeSerialNumber;
DWORD Reserved4;
};](https://image.slidesharecdn.com/rodionovmatrosovvb2014-160216090454/85/Bootkits-Past-Present-Future-Virus-Bulletin-9-320.jpg)
![From Analytics, and Scalability, and UEFI Exploitation by Teddy Reed
Patch attempts to enable BIOS write protection (sets
BIOS_CONTROL[BLE]). Picked up by Subzero](https://image.slidesharecdn.com/rodionovmatrosovvb2014-160216090454/85/Bootkits-Past-Present-Future-Virus-Bulletin-34-320.jpg)
Bootkits: Past, Present & Future - Virus Bulletin
- 1. Bootkits: Past, Present & Future Alexander Matrosov @matrosov Eugene Rodionov @vxradius David Harley @DavidHarleyBlog
- 2. Agenda Modern Bootkits History Legacy BIOS vs. UEFI Boot Environment & Proof of Concept vs. In the Wild Legacy BIOS Bootkit Classification UEFI Bootkits Bootkit Implementation Strategies Attacks against Secure Boot Forensic Software HiddenFsReader CHIPSEC
- 3. Modern Bootkit History 20072007 20082008 20092009 20102010 20112011 20122012 2013201320052005 20142014 eEye BootRoot Mebroot Vbootkit Mebratix Mebrootv2 Olmarik(TDL4) Olmasco(TDL4-based) Vbootkit x64 Vbootkit x64 Rovnix Evil Core Stoned Bootkit Mebromi DeepBoot Stoned Bootkit x64 Gapz VGA Bootkit Dream Boot OldBoot(AndroidBootkit) Microsoft x64 platform gains popularity Secure Boot implemented in Windows 8 In the Wild Proof of Concept
- 4. Legacy BIOS vs. UEFI No more MBR and VBR/IPL code Different hard drive partitioning scheme: GPT (GUID Partition Table) Secure Boot technology is implemented in Windows 8 BIOS BIOS boot code bootmgr Load kernel and boot start drivers winload.efi MBR (Master Boot Record) VBR/IPL (Volume Boot Record/ Initial Program Loader) Load kernel and boot start drivers winload.efi UEFI boot loader (bootmgfw.efi) UEFI boot code UEFI
- 5. The Target of Modern Bootkits (MBR/VBR)
- 6. Classification of MBR/VBR Bootkits Bootkits MBR VBR/IPL MBR Code modification Partition Table modification IPL Code modification BIOS Parameter Block modification TDL4 Olmasco Rovnix Gapz
- 7. IPL Code Modification: Rovnix Win64/Rovnix overwrites bootstrap code of the active partition MBR VBR Bootstrap Code File System Data VBR Malicious Code File System Data Bootstrap Code MBR NTFS bootstrap code (15 sectors) Before Infecting After Infecting Malicious Unsigned Driver Compressed Data “Hasta La Vista, Bootkit: Exploiting the VBR” http://www.welivesecurity.com/2011/08/23/hasta-la-vista-bootkit-exploiting-the-vbr/
- 8. Gapz VBR Bootkit Main features: Relies on Microsoft Windows VBR layout The infections result in modifying only 4 bytes of VBR The patched bytes might differ on various installations jmp BIOS Parameter Block (BPB) VBR code Text Strings 0x55 0xAA 0x000 0x003 0x054 0x19C 0x1FE 0x200 transfer control “Mind the Gapz: The most complex bootkit ever analyzed?” http://www.welivesecurity.com/wp-content/uploads/2013/04/gapz-bootkit-whitepaper.pdf
- 9. Gapz BPB Layout struct BIOS_PARAMETER_BLOCK { WORD BytesPerSector; BYTE SecPerCluster; WORD ReservedSectors; BYTE Reserved[5]; BYTE MediaDescriptorID; WORD Reserved2; WORD SectorsPerTrack; WORD NumberOfHeads; DWORD HiddenSectors; DWORD Reserved3[2]; LONGLONG TotalSectors; LONGLONG StartingCluster; LONGLONG MFTMirrStartingCluster; DWORD ClustersPerMFTRecord; DWORD ClustersPerIndexBuffer; LONGLONG VolumeSerialNumber; DWORD Reserved4; };
- 10. Gapz MBR NTFS File SystemIPLVBR NTFS Volume 0x200 0x1E00 Number of “Hidden Sectors” MBR NTFS File SystemIPL Infected VBR NTFS Volume 0x200 0x1E00 Hard Drive Modified value of number of “Hidden Sectors” Bootkit before infection after infection
- 11. Modern Bootkits ComparisonFunctionality Gapz Olmarik (TDL4) Rovnix (Cidox) Goblin (XPAJ) Olmasco (MaxSS) MBR modification VBR modification Hidden file system type FAT32 custom FAT16 modification custom (TDL4 based) custom Crypto implementation AES-256, RC4, MD5, SHA1, ECC XOR/RC4 Custom (XOR+ROL) RC6 modification Compression algorithm aPlib aPlib Custom TCP/IP network stack implementation
- 12. HiddenFsReader as a Forensic Tool (MBR/VBR)
- 13. HiddenFsReader as a Forensic Tool (MBR/VBR)
- 15. In The Beginning… In 1998-99 CIH (Chernobyl) virus written by a student of Taipei Tatung Institute of Technology in Taiwan infected ~60 million PCs CIH (Chernobyl) erased BIOS ‘ROM’ boot block and boot sectors on a hard drive causing ~1B US dollars in damage
- 16. • Mebromi malware includes BIOS infector & MBR bootkit components • Patches BIOS ROM binary injecting malicious ISA Option ROM with legitimate BIOS image mod utility • Triggers SW SMI 0x29/0x2F to erase SPI flash then write patched BIOS binary Signed BIOS Updates Are Rare • No concept of Secure or Verified Boot • Wonder why TDL4 and likes flourished? No Signature Checks of OS boot loaders (MBR/VBR)
- 17. UEFI BIOS Firmware SEC Pre-EFI Init (PEI) Driver Exec Env (DXE) Boot Dev Select (BDS) Runtime / OS S-CRTM; Init caches/MTRRs; Cache-as-RAM (NEM); Recovery; TPM Init S-CRTM: Measure DXE/BDS Early CPU/PCH Init Memory (DIMMs, DRAM) Init, SMM Init Continue initialization of platform & devices Enum FV, dispatch drivers (network, I/O, service..) Produce Boot and Runtime Services Boot Manager (Select Boot Device) EFI Shell/Apps; OS Boot Loader(s) ExitBootServices. Minimal UEFI services (Variable) ACPI, UEFI SystemTable, SMBIOS table CPU Reset
- 18. UEFI Bootkits Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders System Firmware (SEC/PEI) DXE Driver UEFI Boot Loader Bootx64.efi Bootmgfw.efi DXE Driver UEFI OROM UEFI OROM OS Kernel / Drivers HDD Malware
- 19. Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders System Firmware (SEC/PEI) UEFI Boot Loader Bootx64.efi Bootmgfw.efi OS Kernel / Drivers Malware DXE Driver DXE Driver UEFI OROM UEFI OROM HDD UEFI Bootkits
- 20. Replacing Windows Boot Manager EFI System Partition (ESP) on Fixed Drive ESPEFIMicrosoftBootbootmgfw.efi UEFI technology: say hello to the Windows 8 bootkit! by ITSEC Replacing Fallback Boot Loader ESPEFIBootbootx64.efi UEFI and Dreamboot by Sébastien Kaczmarek, QUARKSLAB Adding New Boot Loader (bootkit.efi) Modified BootOrder / Boot#### EFI variables UEFI Bootkits
- 21. Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders System Firmware (SEC/PEI) UEFI Boot Loader Bootx64.efi Bootmgfw.efi OS Kernel / Drivers Malware DXE Driver DXE Driver UEFI OROM UEFI OROM HDD UEFI Bootkits
- 22. Adding/Replacing DXE Driver Stored on Fixed Drive Not embedded in Firmware Volume (FV) in ROM Modified DriverOrder + Driver#### EFI variables UEFI Bootkits
- 23. Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders System Firmware (SEC/PEI) UEFI Boot Loader Bootx64.efi Bootmgfw.efi OS Kernel / Drivers Malware DXE Driver DXE Driver UEFI OROM UEFI OROM HDD UEFI Bootkits
- 24. Patching UEFI “Option ROM” UEFI DXE Driver in Add-On Card (Network, Storage..) Non-Embedded in FV in ROM Mac EFI Rootkits by @snare, Black Hat USA 2012 UEFI Bootkits
- 25. Replacing OS Loaders (winload.efi, winresume.efi) Patching GUID Partition Table (GPT) UEFI Bootkits
- 26. Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders System Firmware (SEC/PEI) UEFI Boot Loader Bootx64.efi Bootmgfw.efi OS Kernel / Drivers Malware DXE Driver DXE Driver UEFI OROM UEFI OROM HDD UEFI Bootkits
- 27. What about Secure Boot?
- 28. Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders (winload.efi, winresume.efi) System Firmware (SEC/PEI) UEFI OROM UEFI Boot Loader Bootx64.efi Bootmgfw.efi Signed BIOS Update UEFI OROM UEFI App UEFI App DXE Driver DXE Driver OS Kernel / Early Launch Anti-Malware (ELAM) UEFI Secure Boot OS Driver OS Driver Windows 8.1 Secure Boot Secure Boot on MS Windows 8.1
- 29. Hardware I/O Memory Network Graphics UEFI DXE Core / Dispatcher UEFI OS Loaders System Firmware (SEC/PEI) DXE Driver UEFI Boot Loader Bootx64.efi Bootmgfw.efi Signed BIOS Update DXE Driver OS Kernel OS Driver OS Exploit Modify Secure Boot FW or config in ROM Secure Boot bypass possible?
- 30. First Public Windows 8 Secure Boot Bypass (Aug 2013) A Tale Of One Software Bypass Of Windows 8 Secure Boot
- 32. BIOS Attack Surface System FW/BIOS SPI Flash Protection BIOS Update SMRAM Protection Hardware Config. SMI Handlers Secure Boot BIOS Settings (NVRAM, Variables) … Summary of Attacks Against BIOS and Secure Boot
- 34. From Analytics, and Scalability, and UEFI Exploitation by Teddy Reed Patch attempts to enable BIOS write protection (sets BIOS_CONTROL[BLE]). Picked up by Subzero
- 36. CHIPSEC: Platform Security Assessment Framework
- 37. CHIPSEC: Platform Security Assessment Framework chipsec_main.py runs modules (see modules dir below) chipsec_util.py runs manual utilities (see utilcmd dir below) /chipsec /cfg platform specific configuration /hal all the HW stuff you can interact with /helper support for OS/environments /modules modules (tests/tools/PoCs) go here /utilcmd utility commands for chipsec_util
- 38. Known Threats and CHIPSEC modules Issue CHIPSEC Module References SMRAM Locking common.smm CanSecWest 2006 BIOS Keyboard Buffer Sanitization common.bios_kbrd_buffer DEFCON 16 2008 SMRR Configuration common.smrr ITL 2009 CanSecWest 2009 BIOS Protection common.bios_wp BlackHat USA 2009 CanSecWest 2013 Black Hat 2013 NoSuchCon 2013 Flashrom SPI Controller Locking common.spi_lock Flashrom Copernicus BIOS Interface Locking common.bios_ts PoC 2007 Access Control for Secure Boot Keys common.secureboot.keys UEFI 2.4 Spec Access Control for Secure Boot Variables common.secureboot.variables UEFI 2.4 Spec
- 39. BIOS/Firmware Forensics Live system firmware analysis chipsec_util spi info chipsec_util spi dump rom.bin chipsec_util spi read 0x700000 0x100000 bios.bin chipsec_util uefi var-list chipsec_util uefi var-read db D719B2CB-3D3A-4596-A3BC-DAD00E67656F db.bin Offline system firmware analysis chipsec_util uefi keys PK.bin chipsec_util uefi nvram vss bios.bin chipsec_util uefi decode rom.bin chipsec_util decode rom.bin
- 40. How to dump BIOS firmware directly from chip?
- 41. How to dump BIOS firmware directly from chip?
- 42. DEMO TIME
- 44. Thank you for your attention! Eugene Rodionov @vxradius Alexander Matrosov @matrosov David Harley @DavidHarleyBlog