BRLY-LOGOFAIL-2023-013

Memory contents leak / information disclosure vulnerability in DXE driver.

Public Disclosure Date: Jun 19, 2024

CVE ID

CVE-2023-39538

Summary

BINARLY efiXplorer team has discovered a memory contents leak / information disclosure vulnerability. Image->ImageOffset is not validated during parsing of arbitrary BMP file on AMI firmware. The attacker can make it as high as 0xFFFFFFFF and thus display the contents of physical memory (in the form of pixels).

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

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

Book a Demo

Potential Impact

An attacker with local privileged access can exploit this vulnerability to read the contents of the physical memory and use this information to exploit other vulnerabilities in DXE. A malicious code installed as a result of the vulnerability exploitation in a DXE driver could survive across an operating system (OS) boot process and runtime or modify NVRAM area on SPI flash storage (to gain persistence on target platform). Additionally, this vulnerability potentially could be used by threat actors to bypass OS security mechanisms (modify privileged memory or runtime variables), influence on the OS boot process, and in some cases would allow an attacker to hook or modify EFI Runtime services.

Vulnerability Information

BINARLY internal vulnerability identifier: BRLY-LOGOFAIL-2023-013
AMI PSIRT assigned CVE identifier: CVE-2023-39538
CVSS v3.1: 6.0 Medium AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Table of Contents

01.Affected modules

02.Vulnerability description

03.Disclosure timeline

04.Acknowledgements

Affected modules

Module name	Module GUID	Module SHA256
AMITSE	b1da0adf-4f77-4070-a88e-bffe1c60529a	439e73d391b7f7540f6faa58afdc2722bda250468d4a4f7f5f84228c1f77ddbe

Vulnerability description

The pseudocode of the vulnerable function is shown below:

unsigned __int64 __fastcall DecodeBMP(
        BMP_IMAGE_HEADER *Image,
        __int64 ImageSize,
        __int64 *a3,
        unsigned __int64 *a4,
        unsigned __int64 *a5,
        unsigned __int64 *a6)
{
  CHAR8 *v8; // rdi
  unsigned __int64 v9; // rcx
  unsigned __int64 v10; // rax
  __int64 v11; // rax
  unsigned __int64 v13; // r11
  unsigned __int64 PixelWidth; // rdx
  unsigned __int64 PixelHeight; // rcx
  unsigned __int64 v16; // r10
  __int64 v17; // rsi
  unsigned __int64 v18; // r9
  CHAR8 *v19; // r8
  CHAR8 v20; // al
  CHAR8 v21; // al
  unsigned __int64 v22; // rcx
  __int64 v23; // rcx
  __int64 v24; // rcx
  CHAR8 CharB; // al
  UINT32 ImageOffset; // eax

  if ( *(_WORD *)&Image->CharB != 'MB' )
    return 0x8000000000000003ui64;
  if ( Image->CompressionType )
    return 0x8000000000000003ui64;
  // BRLY-LOGOFAIL-2023-013  
  v8 = &Image->CharB + Image->ImageOffset;
  v9 = Image->PixelWidth * (unsigned __int64)Image->PixelHeight;
  if ( v9 >= 0x40000000 )
    return 0x8000000000000003ui64;
  v10 = 4 * v9;
  if ( *a3 )
  {
    if ( *a4 < v10 )
    {
      *a4 = v10;
      return 0x8000000000000005ui64;
    }
  }
  else
  {
    *a4 = v10;
    v11 = sub_500C(4 * v9);
    *a3 = v11;
    if ( !v11 )
      return 0x8000000000000009ui64;
  }
  v13 = 0i64;
  PixelWidth = Image->PixelWidth;
  PixelHeight = Image->PixelHeight;
  v16 = PixelWidth;
  v17 = *a3;
  *a6 = PixelWidth;
  *a5 = PixelHeight;
  if ( (_DWORD)PixelHeight )
  {
    do
    {
      v18 = 0i64;
      v19 = (CHAR8 *)(v17 + 4 * v16 * (PixelHeight - v13 - 1));
      if ( (_DWORD)PixelWidth )
      {
        do
        {
          switch ( Image->BitPerPixel )
          {
            case 1u:
              v24 = 8i64;
              do
              {
                if ( ((unsigned __int8)(1 << --v24) & (unsigned __int8)*v8) != 0 )
                {
                  v19[2] = Image[1].Reserved[0];
                  v19[1] = HIBYTE(Image[1].Size);
                  CharB = BYTE2(Image[1].Size);
                }
                else
                {
                  v19[2] = Image[1].Size;
                  v19[1] = Image[1].CharM;
                  CharB = Image[1].CharB;
                }
                *v19 = CharB;
                if ( v18 < Image->PixelWidth )
                {
                  v19 += 4;
                  ++v18;
                }
              }
              while ( v24 );
              v19 -= 4;
              --v18;
              break;
            case 4u:
              v22 = (unsigned __int64)(unsigned __int8)*v8 >> 4;
              v19[2] = *((_BYTE *)&Image[1].Size + 4 * v22);
              v19[1] = *(&Image[1].CharM + 4 * v22);
              *v19 = *(&Image[1].CharB + 4 * v22);
              if ( v18 < Image->PixelWidth - 1 )
              {
                v19 += 4;
                ++v18;
                v23 = *v8 & 0xF;
                v19[2] = *((_BYTE *)&Image[1].Size + 4 * v23);
                v19[1] = *(&Image[1].CharM + 4 * v23);
                *v19 = *(&Image[1].CharB + 4 * v23);
              }
              break;
            case 8u:
              v19[2] = *((_BYTE *)&Image[1].Size + 4 * (unsigned __int8)*v8);
              v19[1] = *(&Image[1].CharM + 4 * (unsigned __int8)*v8);
              *v19 = *(&Image[1].CharB + 4 * (unsigned __int8)*v8);
              break;
            case 0x18u:
              *v19 = *v8;
              v21 = v8[1];
              v8 += 2;
              v19[1] = v21;
              v19[2] = *v8;
              break;
            default:
              if ( Image->BitPerPixel != 32 || Image->CompressionType )
                return 0x8000000000000003ui64;
              *v19 = *v8;
              v19[1] = v8[1];
              v20 = v8[2];
              v8 += 3;
              v19[2] = v20;
              break;
          }
          PixelWidth = Image->PixelWidth;
          ++v18;
          ++v8;
          v19 += 4;
          v16 = PixelWidth;
        }
        while ( v18 < PixelWidth );
      }
      ImageOffset = Image->ImageOffset;
      if ( (((_BYTE)v8 - (_BYTE)ImageOffset) & 3) != 0 )
        v8 += 4i64 - (((_BYTE)v8 - (_BYTE)ImageOffset) & 3);
      PixelHeight = Image->PixelHeight;
      ++v13;
    }
    while ( v13 < PixelHeight );
  }
  return 0i64;
}

As we can see from the pseudocode, Image->ImageOffset is not validated. The attacker can make it as high as 0xFFFFFFFF and thus display the contents of physical memory (in the form of pixels) at any offset.

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
AMI PSIRT confirmed reported issues	2023-10-05
AMI PSIRT assigned CVE ID	2023-12-01
BINARLY public disclosure date	2024-06-19

Acknowledgements

BINARLY efiXplorer team

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

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.

Book a Demo

Potential Impact

Module name

Module GUID

Module SHA256

AMITSE

b1da0adf-4f77-4070-a88e-bffe1c60529a

439e73d391b7f7540f6faa58afdc2722bda250468d4a4f7f5f84228c1f77ddbe

unsigned __int64 __fastcall DecodeBMP( BMP_IMAGE_HEADER *Image, __int64 ImageSize, __int64 *a3, unsigned __int64 *a4, unsigned __int64 *a5, unsigned __int64 *a6) { CHAR8 *v8; // rdi unsigned __int64 v9; // rcx unsigned __int64 v10; // rax __int64 v11; // rax unsigned __int64 v13; // r11 unsigned __int64 PixelWidth; // rdx unsigned __int64 PixelHeight; // rcx unsigned __int64 v16; // r10 __int64 v17; // rsi unsigned __int64 v18; // r9 CHAR8 *v19; // r8 CHAR8 v20; // al CHAR8 v21; // al unsigned __int64 v22; // rcx __int64 v23; // rcx __int64 v24; // rcx CHAR8 CharB; // al UINT32 ImageOffset; // eax if ( *(_WORD *)&Image->CharB != 'MB' ) return 0x8000000000000003ui64; if ( Image->CompressionType ) return 0x8000000000000003ui64; // BRLY-LOGOFAIL-2023-013 v8 = &Image->CharB + Image->ImageOffset; v9 = Image->PixelWidth * (unsigned __int64)Image->PixelHeight; if ( v9 >= 0x40000000 ) return 0x8000000000000003ui64; v10 = 4 * v9; if ( *a3 ) { if ( *a4 < v10 ) { *a4 = v10; return 0x8000000000000005ui64; } } else { *a4 = v10; v11 = sub_500C(4 * v9); *a3 = v11; if ( !v11 ) return 0x8000000000000009ui64; } v13 = 0i64; PixelWidth = Image->PixelWidth; PixelHeight = Image->PixelHeight; v16 = PixelWidth; v17 = *a3; *a6 = PixelWidth; *a5 = PixelHeight; if ( (_DWORD)PixelHeight ) { do { v18 = 0i64; v19 = (CHAR8 *)(v17 + 4 * v16 * (PixelHeight - v13 - 1)); if ( (_DWORD)PixelWidth ) { do { switch ( Image->BitPerPixel ) { case 1u: v24 = 8i64; do { if ( ((unsigned __int8)(1 << --v24) & (unsigned __int8)*v8) != 0 ) { v19[2] = Image[1].Reserved[0]; v19[1] = HIBYTE(Image[1].Size); CharB = BYTE2(Image[1].Size); } else { v19[2] = Image[1].Size; v19[1] = Image[1].CharM; CharB = Image[1].CharB; } *v19 = CharB; if ( v18 < Image->PixelWidth ) { v19 += 4; ++v18; } } while ( v24 ); v19 -= 4; --v18; break; case 4u: v22 = (unsigned __int64)(unsigned __int8)*v8 >> 4; v19[2] = *((_BYTE *)&Image[1].Size + 4 * v22); v19[1] = *(&Image[1].CharM + 4 * v22); *v19 = *(&Image[1].CharB + 4 * v22); if ( v18 < Image->PixelWidth - 1 ) { v19 += 4; ++v18; v23 = *v8 & 0xF; v19[2] = *((_BYTE *)&Image[1].Size + 4 * v23); v19[1] = *(&Image[1].CharM + 4 * v23); *v19 = *(&Image[1].CharB + 4 * v23); } break; case 8u: v19[2] = *((_BYTE *)&Image[1].Size + 4 * (unsigned __int8)*v8); v19[1] = *(&Image[1].CharM + 4 * (unsigned __int8)*v8); *v19 = *(&Image[1].CharB + 4 * (unsigned __int8)*v8); break; case 0x18u: *v19 = *v8; v21 = v8[1]; v8 += 2; v19[1] = v21; v19[2] = *v8; break; default: if ( Image->BitPerPixel != 32 || Image->CompressionType ) return 0x8000000000000003ui64; *v19 = *v8; v19[1] = v8[1]; v20 = v8[2]; v8 += 3; v19[2] = v20; break; } PixelWidth = Image->PixelWidth; ++v18; ++v8; v19 += 4; v16 = PixelWidth; } while ( v18 < PixelWidth ); } ImageOffset = Image->ImageOffset; if ( (((_BYTE)v8 - (_BYTE)ImageOffset) & 3) != 0 ) v8 += 4i64 - (((_BYTE)v8 - (_BYTE)ImageOffset) & 3); PixelHeight = Image->PixelHeight; ++v13; } while ( v13 < PixelHeight ); } return 0i64; }

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

AMI PSIRT confirmed reported issues

2023-10-05

AMI PSIRT assigned CVE ID

2023-12-01

BINARLY public disclosure date

2024-06-19

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

Potential Impact

Image preview

Vulnerability Information

Image preview

Affected modules

Image preview

Vulnerability description

Image preview

Disclosure timeline

Image preview

Acknowledgements

Image preview

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

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

Potential Impact

Image preview

Vulnerability Information

Image preview

Affected modules

Image preview

Vulnerability description

Image preview

Disclosure timeline

Image preview

Acknowledgements

Image preview

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