BRLY-2022-041

The stack memory contents leak / information disclosure vulnerability in DXE driver.

Public Disclosure Date: Nov 16, 2023

CVE ID

CVE-2023-22330

Vendors Affected

Intel

Products Affected

Intel NUC M15 / BCTGL357 v0077 (Latest)

Summary

BINARLY efiXplorer team has discovered a stack memory contents leak / information disclosure vulnerability that allows a potential attacker to write stack memory to NVRAM variable.

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Potential Impact

An attacker with local privileged access can exploit this vulnerability to read the contents of the stack 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-2022-041
Intel PSIRT assigned CVE identifier: CVE-2023-22330
Intel advisory: INTEL-SA-00917
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 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 / BCTGL357 v0077 (Latest)	AmiTcgPlatformDxe	c290b100e7e5746a448cba16b79a7439acb666031abe80f68651afaa6f635700	A29A63E3-E4E7-495F-8A6A-07738300CBB3

Vulnerability description

The vulnerability exists in the function located at offset 0x2450. This function is part of AMI_TCG_PLATFORM_PROTOCOL protocol interface (Potential function name: ProcessTcgSetup).

The pseudocode for the vulnerable function is shown below:

__int64 ProcessTcgSetup()
{
  //
  // local variables initialization
  //

  Attributes = 3;
  v28 = 0;
  DataSize = 1;
  Data = 0;
  if ( (gBS->LocateProtocol(&SETUP_GUID, 0, &Interface) & 0x8000000000000000) == 0 )
    return (*Interface)();
  result = gBS->LocateProtocol(&EFI_TPM_MP_DRIVER_PROTOCOL_GUID, 0, &v32);
  if ( result >= 0 )
  {
    result = gBS->LocateProtocol(&EFI_TCG_PROTOCOL_GUID, 0, &EfiTcgProtocol);
    if ( result >= 0 )
    {
      result = gBS->LocateProtocol(&TCG_PLATFORM_SETUP_POLICY_GUID, 0, &TcgPlatformSetupPolicy);
      if ( result >= 0 )
      {
        ...
        if ( (gRT->GetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, &Attributes, &DataSize, &Data) & 0x8000000000000000) == 0 )
        {
          LOBYTE(v7) = v13;
          if ( Data == v13 )
          {
            if ( v13 != (((v30 | v31) & 1) == 0) )
              v19 = 1;
          }
          else
          {
            Data = v13;
            sub_4D60(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
          }
        }
        else
        {
          Data = v13;
          gRT->SetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
        }
        if ( v19 )
        {
          v13 = ((v30 | v31) & 1) == 0;
          Data = v13;
          v14 = 0;
          v19 = 0;
          sub_4D60(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
        }
        ...
      }
    }
  }
  return result;
}

Consider the following code snippet:

DataSize = 1;
if ( gRT->GetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, &Attributes, &DataSize, &Data) == EFI_SUCCESS )
{
  ...
}
else
{
  Data = v13;
  gRT->SetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
}

As we can see from the pseudocode, for the TpmOldvar variable gRT->SetVariable() service is called with the DataSize value, which can be overwritten inside the gRT->GetVariable() service.

Thus, a potential attacker can write X - 1 bytes from the stack to NVRAM if writes any buffer of length X > 1 to the TpmOldvar NVRAM variable before next system boot.

In order to fix this vulnerability, the DataSize variable must be initialized before gRT->SetVariable().

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 (YYYY-MM-dd)
Intel PSIRT is notified	2022-12-19
Intel PSIRT assigned CVE number	2023-02-28
Intel PSIRT provide patch release	2023-08-08
BINARLY public disclosure date	2023-11-16

Acknowledgements

BINARLY efiXplorer team

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BRLY-2022-041

The stack memory contents leak / information disclosure vulnerability in DXE driver.

Public Disclosure Date: Nov 16, 2023

CVE ID

CVE-2023-22330

Vendors Affected

Intel

Products Affected

Intel NUC M15 / BCTGL357 v0077 (Latest)

Summary

BINARLY efiXplorer team has discovered a stack memory contents leak / information disclosure vulnerability that allows a potential attacker to write stack memory to NVRAM variable.

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

Vulnerability Information

BINARLY internal vulnerability identifier: BRLY-2022-041
Intel PSIRT assigned CVE identifier: CVE-2023-22330
Intel advisory: INTEL-SA-00917
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 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 / BCTGL357 v0077 (Latest)	AmiTcgPlatformDxe	c290b100e7e5746a448cba16b79a7439acb666031abe80f68651afaa6f635700	A29A63E3-E4E7-495F-8A6A-07738300CBB3

Vulnerability description

The vulnerability exists in the function located at offset 0x2450. This function is part of AMI_TCG_PLATFORM_PROTOCOL protocol interface (Potential function name: ProcessTcgSetup).

The pseudocode for the vulnerable function is shown below:

__int64 ProcessTcgSetup()
{
  //
  // local variables initialization
  //

  Attributes = 3;
  v28 = 0;
  DataSize = 1;
  Data = 0;
  if ( (gBS->LocateProtocol(&SETUP_GUID, 0, &Interface) & 0x8000000000000000) == 0 )
    return (*Interface)();
  result = gBS->LocateProtocol(&EFI_TPM_MP_DRIVER_PROTOCOL_GUID, 0, &v32);
  if ( result >= 0 )
  {
    result = gBS->LocateProtocol(&EFI_TCG_PROTOCOL_GUID, 0, &EfiTcgProtocol);
    if ( result >= 0 )
    {
      result = gBS->LocateProtocol(&TCG_PLATFORM_SETUP_POLICY_GUID, 0, &TcgPlatformSetupPolicy);
      if ( result >= 0 )
      {
        ...
        if ( (gRT->GetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, &Attributes, &DataSize, &Data) & 0x8000000000000000) == 0 )
        {
          LOBYTE(v7) = v13;
          if ( Data == v13 )
          {
            if ( v13 != (((v30 | v31) & 1) == 0) )
              v19 = 1;
          }
          else
          {
            Data = v13;
            sub_4D60(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
          }
        }
        else
        {
          Data = v13;
          gRT->SetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
        }
        if ( v19 )
        {
          v13 = ((v30 | v31) & 1) == 0;
          Data = v13;
          v14 = 0;
          v19 = 0;
          sub_4D60(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
        }
        ...
      }
    }
  }
  return result;
}

Consider the following code snippet:

DataSize = 1;
if ( gRT->GetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, &Attributes, &DataSize, &Data) == EFI_SUCCESS )
{
  ...
}
else
{
  Data = v13;
  gRT->SetVariable(L"TpmOldvar", &TC_EFI_GLOBAL_VARIABLE_GUID, Attributes, DataSize, &Data);
}

As we can see from the pseudocode, for the TpmOldvar variable gRT->SetVariable() service is called with the DataSize value, which can be overwritten inside the gRT->GetVariable() service.

Thus, a potential attacker can write X - 1 bytes from the stack to NVRAM if writes any buffer of length X > 1 to the TpmOldvar NVRAM variable before next system boot.

In order to fix this vulnerability, the DataSize variable must be initialized before gRT->SetVariable().

Disclosure timeline

Disclosure Activity	Date (YYYY-MM-dd)
Intel PSIRT is notified	2022-12-19
Intel PSIRT assigned CVE number	2023-02-28
Intel PSIRT provide patch release	2023-08-08
BINARLY public disclosure date	2023-11-16

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

Image preview

Vulnerability Information

Image preview

Affected Intel firmware confirmed to be impacted by Binarly team

Image preview

Vulnerability description

Image preview

Disclosure timeline

Image preview

Acknowledgements

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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 Intel firmware confirmed to be impacted by Binarly team

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