[BRLY-LOGOFAIL-2023-021] Out-of-bounds Read in DXE driver

Vulnerability Information

• BINARLY internal vulnerability identifier: BRLY-LOGOFAIL-2023-021
• CVSS v3.1: 3.2 Low AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:L/A:N

Affected modules with confirmed impact by Binarly team

Vulnerability description

The pseudocode of the vulnerable function is shown below:

__int64 __fastcall GetDimensions(_BYTE *Image)
{
  char v2; // di
  unsigned __int8 v3; // r10
  unsigned __int8 v4; // bl
  unsigned __int8 MarkerType; // cl
  __int64 v6; // rax
  __int64 v8; // rax
  char v9; // al
  _BYTE *v10; // rdx
  _QWORD *v11; // r8
  unsigned __int8 v12; // r9
  __int64 v13; // rdx
  __int64 v14; // r11
  unsigned __int16 Len; // [rsp+30h] [rbp+8h]

  v2 = 0;
  v3 = 0;
  v4 = 0;
  if ( *Image != 0xFF || Image[1] != 0xD8 )
    return 0i64;
  while ( 1 )
  {
    MarkerType = Image[1];
    if ( MarkerType != 0xD8 )
      break;
    Image += 2;
LABEL_27:
    if ( *Image != 0xFF )
      return 0i64;
  }
  if ( MarkerType == 0xD9 )
    goto LABEL_30;
  if ( !MarkerType )
    return 0i64;
  if ( (MarkerType & 0xF0) == 0xE0 )
  {
LABEL_26:
    v9 = Image[3];
    v10 = Image + 2;
    LOBYTE(Len) = v9;
    HIBYTE(Len) = *v10;
    // BRLY-LOGOFAIL-2023-021: Image pointer is updated with value coming from the image (Len), without validation
    Image = &v10[Len];
    goto LABEL_27;
  }
  if ( MarkerType == 0xC0 )
  {
    v2 |= 2u;
    qword_95FC0 = (Image + 2);
    goto LABEL_26;
  }
  if ( MarkerType == 0xC4 )
  {
    v6 = v3++;
    qword_96560[v6] = (Image + 4);
    goto LABEL_26;
  }
  if ( (MarkerType & 0xF0) == 0xC0 )
  {
    if ( MarkerType > 0xC0u && MarkerType < 0xD0u )
      return 0i64;
    goto LABEL_26;
  }
  if ( MarkerType != 0xDA )
  {
    if ( MarkerType == 0xDB )
    {
      v8 = v4++;
      qword_95EA0[v8] = (Image + 4);
    }
    else if ( MarkerType == 0xDD )
    {
      LOBYTE(word_95490) = Image[5];
      HIBYTE(word_95490) = Image[4];
    }
    else if ( (MarkerType & 0xF8) != 0xD0
           && (MarkerType == 0xDC || MarkerType == 0xDE || MarkerType == 0xDF || (MarkerType + 16) > 0xEu) )
    {
      return 0i64;
    }
    goto LABEL_26;
  }
  qword_95F10 = (Image + 14);
LABEL_30:
  if ( v4 == 1 )
  {
    v4 = 2;
    qword_95EA8 = qword_95EA0[0] + 65;
  }
  if ( v3 == 1 )
  {
    v11 = &unk_96568;
    do
    {
      v12 = 0;
      v13 = 0i64;
      v14 = qword_96560[v3 - 1];
      do
        v12 += *(v14 + v13++ + 1);
      while ( v13 < 16 );
      ++v3;
      *v11++ = v12 + v14 + 17;
    }
    while ( v3 < 4u );
  }
  if ( v3 != 4 || v4 != 2 || (v2 & 2) == 0 )
    return 0i64;
  sub_5D26C(2u, 4u);
  return 1i64;
}

As we can see from the pseudocode, the JPEG Marker length, read from the image and stored in variable Len, is used to update the value of ImagePtr without any validation. The attacker can arbitrarily set wLen thus making ImagePtr point anywhere in memory.

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.
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Acknowledgements

BINARLY efiXplorer team