BRLY-LOGOFAIL-2023-002

Memory Corruption vulnerability in DXE driver.

Public Disclosure Date: Jun 19, 2024

CVE ID

CVE-2023-40238

Summary

BINARLY efiXplorer team has discovered an OOB Write vulnerability in the RLE8 decode routine during BMP file processing in Insyde firmware.

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Potential Impact

An attacker with local 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-LOGOFAIL-2023-002
Insyde PSIRT assigned CVE identifier: CVE-2023-40238
CVSS v3.1: 8.2 High AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Table of Contents

01.Affected modules

02.Vulnerability description

03.Disclosure timeline

04.Acknowledgements

Affected modules

Module name	Module GUID	Module SHA256
BmpDecoderDxe	a9f634a5-29f1-4456-a9d5-6e24b88bdb65	02034e3bdc02ef843651611c1f97f8f2a1deb0be78f9085ac40077eba4260128

Vulnerability description

The pseudocode of the vulnerable function is shown below:

__int64 __fastcall DecodeRLE8(
        EFI_GRAPHICS_OUTPUT_BLT_PIXEL *BltOutput,
        unsigned __int8 *a2,
        __int64 a3,
        BMP_IMAGE *Image)
{
  unsigned __int64 PixelHeight; // rax
  char v5; // r15
  unsigned __int64 i; // r11
  __int64 PixelWidth; // rbx
  unsigned __int64 v11; // r9
  char v12; // bp
  EFI_GRAPHICS_OUTPUT_BLT_PIXEL *BltEntry; // r8
  __int64 v14; // rax
  unsigned __int8 *v15; // rsi
  __int64 v16; // r10
  __int64 v17; // rcx
  char v18; // si
  __int64 v19; // rax

  PixelHeight = Image->BmpHeader.PixelHeight;
  v5 = 0;
  for ( i = 0i64; i <= PixelHeight; ++i )
  {
    if ( v5 )
      break;
    PixelWidth = Image->BmpHeader.PixelWidth;
    v11 = 0i64;
    v12 = 0;
    // BRLY-LOGOFAIL-2023-002
    BltEntry = &BltOutput[PixelWidth * (PixelHeight - i - 1)];
    do
    {
      if ( v12 )
        break;
      v14 = *a2;
      v15 = a2 + 1;
      v16 = a2[1];
      a2 += 2;
      if ( (_BYTE)v14 )
      {
        v17 = (unsigned int)v14;
        v11 += v14;
        do
        {
          BltEntry->Red = *(_BYTE *)(a3 + 4 * v16 + 2);// arbitrary write
          BltEntry->Green = *(_BYTE *)(a3 + 4 * v16 + 1);// arbitrary write
          BltEntry->Blue = *(_BYTE *)(a3 + 4 * v16);// arbitrary write
          ++BltEntry;
          --v17;
        }
        while ( v17 );
      }
      else if ( (_BYTE)v16 )
      {
        if ( (_DWORD)v16 == 1 )
        {
          v5 = 1;
          v12 = 1;
        }
        else if ( (_DWORD)v16 == 2 )
        {
          v11 += *a2;
          i += v15[2];
          a2 = v15 + 3;
          BltEntry = &BltOutput[v11 + (unsigned int)PixelWidth * (Image->BmpHeader.PixelHeight - i - 1)];
        }
        else
        {
          v11 += v16;
          v18 = v16;
          do
          {
            v19 = *a2++;
            BltEntry->Red = *(_BYTE *)(a3 + 4 * v19 + 2);
            BltEntry->Green = *(_BYTE *)(a3 + 4i64 * (unsigned int)v19 + 1);
            BltEntry->Blue = *(_BYTE *)(a3 + 4i64 * (unsigned int)v19);
            ++BltEntry;
            --v16;
          }
          while ( v16 );
          if ( (v18 & 1) != 0 )
            ++a2;
        }
      }
      else
      {
        v12 = 1;
      }
      LODWORD(PixelWidth) = Image->BmpHeader.PixelWidth;
    }
    while ( v11 <= (unsigned int)PixelWidth );
    PixelHeight = Image->BmpHeader.PixelHeight;
  }
  return 0i64;
}

Where DecodeRLE8 function will be called from the DecodeBMP function:

if ( Image->BmpHeader.CompressionType == 1 )
{
    if ( v18 )
      sub_330(*a3, v18, 0i64);
    DecodeRLE8(v22, v17, &Image->field_36, Image);
    return 0i64;
}
}

As we can see from the pseudocode, when BmpHeader->PixelHeight (controllable by the attacker) is equal to 0, BltEntry pointer will be located below BltOutput pointer ((0 - 0 - 1) * BmpHeader->PixelWidth = - BmpHeader->PixelWidth). Thus, by subsequent write operations, a potential attacker can write data to a controllable address (in the physical memory below BltOutput address). This vulnerability could lead to the execution of arbitrary code during the DXE phase.

Disclosure timeline

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

Disclosure Activity	Date (YYYY-mm-dd)
Lenovo PSIRT is notified	2023-06-21
Lenovo ID (LEN-132940) is assigned	2023-06-22
CERT/CC is notified	2023-07-10
Insyde PSIRT confirmed reported issues	2023-09-10
Insyde PSIRT assigned CVE ID	2023-11-27
Insyde advisory release date	2023-12-06
BINARLY public disclosure date	2024-06-19

Acknowledgements

BINARLY efiXplorer team

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BRLY-LOGOFAIL-2023-002

Memory Corruption vulnerability in DXE driver.

Public Disclosure Date: Jun 19, 2024

CVE ID

CVE-2023-40238

Summary

BINARLY efiXplorer team has discovered an OOB Write vulnerability in the RLE8 decode routine during BMP file processing in Insyde firmware.

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Book a live tour to watch Binarly validate SBOM/CBOM, surface exploitable risks, and chart a path to post-quantum readiness.

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Potential Impact

Vulnerability Information

BINARLY internal vulnerability identifier: BRLY-LOGOFAIL-2023-002
Insyde PSIRT assigned CVE identifier: CVE-2023-40238
CVSS v3.1: 8.2 High AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Table of Contents

01.Affected modules

02.Vulnerability description

03.Disclosure timeline

04.Acknowledgements

Affected modules

Module name	Module GUID	Module SHA256
BmpDecoderDxe	a9f634a5-29f1-4456-a9d5-6e24b88bdb65	02034e3bdc02ef843651611c1f97f8f2a1deb0be78f9085ac40077eba4260128

Vulnerability description

The pseudocode of the vulnerable function is shown below:

__int64 __fastcall DecodeRLE8(
        EFI_GRAPHICS_OUTPUT_BLT_PIXEL *BltOutput,
        unsigned __int8 *a2,
        __int64 a3,
        BMP_IMAGE *Image)
{
  unsigned __int64 PixelHeight; // rax
  char v5; // r15
  unsigned __int64 i; // r11
  __int64 PixelWidth; // rbx
  unsigned __int64 v11; // r9
  char v12; // bp
  EFI_GRAPHICS_OUTPUT_BLT_PIXEL *BltEntry; // r8
  __int64 v14; // rax
  unsigned __int8 *v15; // rsi
  __int64 v16; // r10
  __int64 v17; // rcx
  char v18; // si
  __int64 v19; // rax

  PixelHeight = Image->BmpHeader.PixelHeight;
  v5 = 0;
  for ( i = 0i64; i <= PixelHeight; ++i )
  {
    if ( v5 )
      break;
    PixelWidth = Image->BmpHeader.PixelWidth;
    v11 = 0i64;
    v12 = 0;
    // BRLY-LOGOFAIL-2023-002
    BltEntry = &BltOutput[PixelWidth * (PixelHeight - i - 1)];
    do
    {
      if ( v12 )
        break;
      v14 = *a2;
      v15 = a2 + 1;
      v16 = a2[1];
      a2 += 2;
      if ( (_BYTE)v14 )
      {
        v17 = (unsigned int)v14;
        v11 += v14;
        do
        {
          BltEntry->Red = *(_BYTE *)(a3 + 4 * v16 + 2);// arbitrary write
          BltEntry->Green = *(_BYTE *)(a3 + 4 * v16 + 1);// arbitrary write
          BltEntry->Blue = *(_BYTE *)(a3 + 4 * v16);// arbitrary write
          ++BltEntry;
          --v17;
        }
        while ( v17 );
      }
      else if ( (_BYTE)v16 )
      {
        if ( (_DWORD)v16 == 1 )
        {
          v5 = 1;
          v12 = 1;
        }
        else if ( (_DWORD)v16 == 2 )
        {
          v11 += *a2;
          i += v15[2];
          a2 = v15 + 3;
          BltEntry = &BltOutput[v11 + (unsigned int)PixelWidth * (Image->BmpHeader.PixelHeight - i - 1)];
        }
        else
        {
          v11 += v16;
          v18 = v16;
          do
          {
            v19 = *a2++;
            BltEntry->Red = *(_BYTE *)(a3 + 4 * v19 + 2);
            BltEntry->Green = *(_BYTE *)(a3 + 4i64 * (unsigned int)v19 + 1);
            BltEntry->Blue = *(_BYTE *)(a3 + 4i64 * (unsigned int)v19);
            ++BltEntry;
            --v16;
          }
          while ( v16 );
          if ( (v18 & 1) != 0 )
            ++a2;
        }
      }
      else
      {
        v12 = 1;
      }
      LODWORD(PixelWidth) = Image->BmpHeader.PixelWidth;
    }
    while ( v11 <= (unsigned int)PixelWidth );
    PixelHeight = Image->BmpHeader.PixelHeight;
  }
  return 0i64;
}

Where DecodeRLE8 function will be called from the DecodeBMP function:

if ( Image->BmpHeader.CompressionType == 1 )
{
    if ( v18 )
      sub_330(*a3, v18, 0i64);
    DecodeRLE8(v22, v17, &Image->field_36, Image);
    return 0i64;
}
}

Disclosure timeline

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

Disclosure Activity	Date (YYYY-mm-dd)
Lenovo PSIRT is notified	2023-06-21
Lenovo ID (LEN-132940) is assigned	2023-06-22
CERT/CC is notified	2023-07-10
Insyde PSIRT confirmed reported issues	2023-09-10
Insyde PSIRT assigned CVE ID	2023-11-27
Insyde advisory release date	2023-12-06
BINARLY public disclosure date	2024-06-19

Acknowledgements

BINARLY efiXplorer team

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Book a live tour to watch Binarly validate SBOM/CBOM, surface exploitable risks with reachability and exploitation maturity scoring, and chart a measurable path to post-quantum readiness.

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Potential Impact

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Vulnerability Information

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Affected modules

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Vulnerability description

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Disclosure timeline

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Acknowledgements

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Potential Impact

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Vulnerability Information

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Affected modules

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Vulnerability description

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Disclosure timeline

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Acknowledgements

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Get started today, Ship and Buy Software You Can Prove Is Safe