BRLY-2022-001

Stack buffer overflow vulnerability leads to arbitrary code execution in a DXE driver on Intel platform.

Public Disclosure Date: Nov 9, 2022

CVE ID

CVE-2022-32569

Summary

BINARLY efiXplorer team has discovered a stack overflow vulnerability that allows a local root user to access a UEFI DXE driver and execute arbitrary code.

Potential Impact

An attacker with local privileged access can exploit this vulnerability to elevate privileges from ring 3 or ring 0 (depends on the operating system) to a DXE driver and execute arbitrary code. Malicious code installed as a result of this exploitation could survive operating system (OS) boot process and runtime, or modify NVRAM area on the SPI flash storage (to gain persistence). Additionally, threat actors could use this vulnerability to bypass OS security mechanisms (modify privileged memory or runtime variables), influence OS boot process, and in some cases allow an attacker to hook or modify EFI Runtime services.

Vulnerability Information

BINARLY internal vulnerability identifier: BRLY-2022-001
Intel PSIRT assigned CVE identifier: CVE-2022-32569
FwHunt rule: BRLY-2022-001
CVSS v3.1: 7.5 High AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Table of Contents

01.Affected Intel firmware confirmed to be impacted by Binarly team

02.Vulnerability description

03.Disclosure timeline

04.Acknowledgements

Affected Intel firmware confirmed to be impacted by Binarly team

Device/Firmware	File Name	SHA256 (File PE32 section)	File GUID
Intel NUC M15	Setup	e625cb142a0140b795fd638e83b5dd751b7426312ac92a4397d9eb3f935b17b5	899407D7-99FE-43D8-9A21-79EC328CAC21

Vulnerability description

The vulnerability exists in the notifier for AMI_SETUP_NVRAM_UPDATE located at offset 0x14D48. The pseudocode for this notifier is shown below:

char __fastcall AmiSetupNvramUpdateCallback(EFI_CAPSULE_HEADER **CapsuleHeaderArray)
{
  __int64 Status; // rax
  __int64 Status_1; // rbx
  UINTN v4; // rdx
  void **v5; // r8
  char v6; // dl
  unsigned __int8 v7; // bl
  char v8; // dl
  int v9; // ecx
  int v10; // edx
  EFI_MEMORY_TYPE MemoryType; // ecx
  UINTN v12; // rdx
  EFI_PHYSICAL_ADDRESS v13; // r8
  void *v15; // [rsp+30h] [rbp-50h] BYREF
  void *Interface; // [rsp+38h] [rbp-48h] BYREF
  void *v17; // [rsp+40h] [rbp-40h] BYREF
  char MeSetupStorageData[17]; // [rsp+48h] [rbp-38h] BYREF
  char MeBackupStorageData[17]; // [rsp+60h] [rbp-20h] BYREF
  EFI_MEMORY_TYPE PoolType; // [rsp+B0h] [rbp+30h] BYREF
  UINTN DataSize; // [rsp+B8h] [rbp+38h] BYREF

  memset(MeSetupStorageData, 0, sizeof(MeSetupStorageData));
  memset(MeBackupStorageData, 0, sizeof(MeBackupStorageData));
  Status = gBS->LocateProtocol(&AMI_SETUP_NVRAM_UPDATE_GUID, 0, &Interface);
  if ( Status >= 0 )
  {
    Status_1 = gBS->LocateProtocol(&ProprietaryProtocol_2, 0, &v17);
    LOBYTE(Status) = sub_1D8C4();
    if ( !Status && Status_1 >= 0 )
    {
      DataSize = 17;
      gRT->GetVariable(L"MeSetupStorage", &gVariableGuid, 0, &DataSize, MeSetupStorageData);
      gRT->GetVariable(L"MeBackupStorage", &gVariableGuid, 0, &DataSize, MeBackupStorageData);
      DataSize = 53;
      gRT->GetVariable(L"MeSetup", &gVariableGuid, 0, &DataSize, &unk_27E60);
      if ( MeSetupStorageData[12] != MeBackupStorageData[12] && !byte_27E8A && MeSetupStorageData[12] == 1 )
        sub_1CAB8();
      if ( MeSetupStorageData[2] != MeBackupStorageData[2] )
      {
        gMemoryType = 1;
        if ( MeSetupStorageData[2] )
        {
          sub_1CCB8();
        }
        else if ( (gBS->LocateProtocol(&ProprietaryProtocol_2, 0, &v15) & 0x8000000000000000) == 0 )
        {
          (*(v15 + 8))(&PoolType, v4, v5);
          if ( PoolType != EfiBootServicesCode && !sub_1D8C4() )
            sub_1C704(6, v6, 0);
        }
      }
      v7 = MeSetupStorageData[1];
      if ( MeSetupStorageData[1] != MeBackupStorageData[1] && !sub_1D8C4() )
        sub_1C704(7, v8, v7);
      if ( MeSetupStorageData[0] != MeBackupStorageData[0] )
      {
        gMemoryType = 1;
        if ( MeSetupStorageData[0] == 1 )
        {
          v9 = 4;
          v10 = 0;
        }
        else
        {
          v9 = 0;
          v10 = 4;
        }
        sub_1CDAC(v9, v10);
      }
      MemoryType = gMemoryType;
      if ( MeSetupStorageData[5] != MeBackupStorageData[5] )
        MemoryType = EfiLoaderCode;
      gMemoryType = MemoryType;
      LOBYTE(MemoryType) = MeSetupStorageData[10];
      if ( MeSetupStorageData[10] != MeBackupStorageData[10] )
      {
        gMemoryType = 1;
        sub_1C91C(MeSetupStorageData[10]);
      }
      if ( MeSetupStorageData[11] != MeBackupStorageData[11] )
        sub_1CF58(MeSetupStorageData[11]);
      if ( MeSetupStorageData[15] != MeBackupStorageData[15] )
        sub_1D544(MemoryType, MeSetupStorageData[15]);
      if ( MeSetupStorageData[16] != MeBackupStorageData[16] )
        sub_1D6C8(MemoryType, MeSetupStorageData[16]);
      LOBYTE(Status) = gRT->SetVariable(L"MeBackupStorage", &gVariableGuid, 2, 0x11, MeSetupStorageData);
      if ( CapsuleHeaderArray )
        LOBYTE(Status) = (gBS->CloseEvent)(CapsuleHeaderArray, v12, v13);
    }
  }
  return Status;
}

Consider the following code snippet:

DataSize = 17;
gRT->GetVariable(L"MeSetupStorage", &gVariableGuid, 0, &DataSize, MeSetupStorageData);
gRT->GetVariable(L"MeBackupStorage", &gVariableGuid, 0, &DataSize, MeBackupStorageData);

An attacker can change the values of the MeSetupStorage and MeBackupStorage variables. If the size of the value of the MeSetupStorageData variable is greater than 17, then after the first call to the GetVariable service, the DataSize variable will be overwritten (this means that the attacker is in control of the DataSize variable). The second call to GetVariable (for the MeBackupStorage variable) can lead to a stack overflow and arbitrary code execution.

Disclosure timeline

This vulnerability is subject to a 90 day disclosure deadline. After 90 days elapsed or a patch has been made broadly available (whichever is earlier), the vulnerability report will become visible to the public.

Disclosure Activity	Date
Intel PSIRT is notified	2022-01-17
Intel PSIRT confirmed reported issue	2022-02-09
Intel PSIRT assigned CVE number	2022-11-08
Intel PSIRT provide patch release	2022-11-08
BINARLY public disclosure date	2022-11-09

Acknowledgements

BINARLY efiXplorer team

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Potential Impact

Device/Firmware

File Name

SHA256 (File PE32 section)

File GUID

Intel NUC M15

Setup

e625cb142a0140b795fd638e83b5dd751b7426312ac92a4397d9eb3f935b17b5

899407D7-99FE-43D8-9A21-79EC328CAC21

char __fastcall AmiSetupNvramUpdateCallback(EFI_CAPSULE_HEADER **CapsuleHeaderArray) { __int64 Status; // rax __int64 Status_1; // rbx UINTN v4; // rdx void **v5; // r8 char v6; // dl unsigned __int8 v7; // bl char v8; // dl int v9; // ecx int v10; // edx EFI_MEMORY_TYPE MemoryType; // ecx UINTN v12; // rdx EFI_PHYSICAL_ADDRESS v13; // r8 void *v15; // [rsp+30h] [rbp-50h] BYREF void *Interface; // [rsp+38h] [rbp-48h] BYREF void *v17; // [rsp+40h] [rbp-40h] BYREF char MeSetupStorageData[17]; // [rsp+48h] [rbp-38h] BYREF char MeBackupStorageData[17]; // [rsp+60h] [rbp-20h] BYREF EFI_MEMORY_TYPE PoolType; // [rsp+B0h] [rbp+30h] BYREF UINTN DataSize; // [rsp+B8h] [rbp+38h] BYREF memset(MeSetupStorageData, 0, sizeof(MeSetupStorageData)); memset(MeBackupStorageData, 0, sizeof(MeBackupStorageData)); Status = gBS->LocateProtocol(&AMI_SETUP_NVRAM_UPDATE_GUID, 0, &Interface); if ( Status >= 0 ) { Status_1 = gBS->LocateProtocol(&ProprietaryProtocol_2, 0, &v17); LOBYTE(Status) = sub_1D8C4(); if ( !Status && Status_1 >= 0 ) { DataSize = 17; gRT->GetVariable(L"MeSetupStorage", &gVariableGuid, 0, &DataSize, MeSetupStorageData); gRT->GetVariable(L"MeBackupStorage", &gVariableGuid, 0, &DataSize, MeBackupStorageData); DataSize = 53; gRT->GetVariable(L"MeSetup", &gVariableGuid, 0, &DataSize, &unk_27E60); if ( MeSetupStorageData[12] != MeBackupStorageData[12] && !byte_27E8A && MeSetupStorageData[12] == 1 ) sub_1CAB8(); if ( MeSetupStorageData[2] != MeBackupStorageData[2] ) { gMemoryType = 1; if ( MeSetupStorageData[2] ) { sub_1CCB8(); } else if ( (gBS->LocateProtocol(&ProprietaryProtocol_2, 0, &v15) & 0x8000000000000000) == 0 ) { (*(v15 + 8))(&PoolType, v4, v5); if ( PoolType != EfiBootServicesCode && !sub_1D8C4() ) sub_1C704(6, v6, 0); } } v7 = MeSetupStorageData[1]; if ( MeSetupStorageData[1] != MeBackupStorageData[1] && !sub_1D8C4() ) sub_1C704(7, v8, v7); if ( MeSetupStorageData[0] != MeBackupStorageData[0] ) { gMemoryType = 1; if ( MeSetupStorageData[0] == 1 ) { v9 = 4; v10 = 0; } else { v9 = 0; v10 = 4; } sub_1CDAC(v9, v10); } MemoryType = gMemoryType; if ( MeSetupStorageData[5] != MeBackupStorageData[5] ) MemoryType = EfiLoaderCode; gMemoryType = MemoryType; LOBYTE(MemoryType) = MeSetupStorageData[10]; if ( MeSetupStorageData[10] != MeBackupStorageData[10] ) { gMemoryType = 1; sub_1C91C(MeSetupStorageData[10]); } if ( MeSetupStorageData[11] != MeBackupStorageData[11] ) sub_1CF58(MeSetupStorageData[11]); if ( MeSetupStorageData[15] != MeBackupStorageData[15] ) sub_1D544(MemoryType, MeSetupStorageData[15]); if ( MeSetupStorageData[16] != MeBackupStorageData[16] ) sub_1D6C8(MemoryType, MeSetupStorageData[16]); LOBYTE(Status) = gRT->SetVariable(L"MeBackupStorage", &gVariableGuid, 2, 0x11, MeSetupStorageData); if ( CapsuleHeaderArray ) LOBYTE(Status) = (gBS->CloseEvent)(CapsuleHeaderArray, v12, v13); } } return Status; }

Disclosure Activity

Date

Intel PSIRT is notified

2022-01-17

Intel PSIRT confirmed reported issue

2022-02-09

Intel PSIRT assigned CVE number

2022-11-08

Intel PSIRT provide patch release

2022-11-08

BINARLY public disclosure date

2022-11-09

Potential Impact

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Vulnerability Information

Image preview

Affected Intel firmware confirmed to be impacted by Binarly team

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Vulnerability description

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Disclosure timeline

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Acknowledgements

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See if you are impacted now with our Firmware Vulnerability Scanner

Potential Impact

Image preview

Vulnerability Information

Image preview

Affected Intel firmware confirmed to be impacted by Binarly team

Image preview

Vulnerability description

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Disclosure timeline

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Acknowledgements

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See if you are impacted now with our Firmware Vulnerability Scanner