BRLY-2022-159

Memory contents leak / information disclosure vulnerability in DXE driver on Dell platform.

Public Disclosure Date: Jun 21, 2023

CVE ID

CVE-2023-28060

Summary

BINARLY efiXplorer team has discovered a memory contents leak / information disclosure vulnerability that allows a potential attacker to dump stack memory or global memory into an NVRAM variable. This in turn could help building a successful attack vector based on exploiting a memory corruption vulnerability.

Potential Impact

An attacker with high physical access can exploit this vulnerability to read the contents of stack memory or global memory. This information could help with exploitation of other vulnerabilities in DXE 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-2022-159
Dell PSIRT assigned CVE identifier: CVE-2023-28060
DSA identifier: DSA-2023-099/DSA-2023-204
CVSS v3.1: 4.9 Medium AV:P/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Table of Contents

01.Affected Dell firmware

02.Vulnerability description

03.Disclosure timeline

04.Acknowledgements

Affected Dell firmware

Product	Firmware version	CPU	Module name	Module GUID	Module SHA256
Latitude 3120	0.1.13.1	AMD	9BCEDB6D-13CA-473E-B605-8A47688729FA	9bcedb6d-13ca-473e-b605-8a47688729fa	adc756cd7143c8c1ec9e1f776aa1c7cee49da09f6e02b5bc609bc6969d977dcb

Vulnerability description

Let's take Latitude 3120's firmware (version: 0.1.13.1, module sha256: adc756cd7143c8c1ec9e1f776aa1c7cee49da09f6e02b5bc609bc6969d977dcb) as an example.

The following code in the module actually allows leaking memory:

a call to a gRT->GetVariable() offset: 0xa65
a call to a gRT->SetVariable() offset: 0xa9c

EFI_STATUS __fastcall sub_8AC()
{
  EFI_GUID VendorGuid; // [rsp+30h] [rbp-D0h] BYREF
  EFI_GUID v2; // [rsp+40h] [rbp-C0h] BYREF
  EFI_GUID v3; // [rsp+50h] [rbp-B0h] BYREF
  char Data[226]; // [rsp+60h] [rbp-A0h] BYREF
  __int16 v5; // [rsp+142h] [rbp+42h]
  int v6[2]; // [rsp+300h] [rbp+200h] BYREF
  char v7; // [rsp+30Ah] [rbp+20Ah]
  char v8; // [rsp+930h] [rbp+830h]
  UINT32 Attributes; // [rsp+A90h] [rbp+990h] BYREF
  char v10; // [rsp+A98h] [rbp+998h] BYREF
  int v11; // [rsp+A99h] [rbp+999h]
  __int16 v12; // [rsp+A9Dh] [rbp+99Dh]
  UINTN DataSize; // [rsp+AA0h] [rbp+9A0h] BYREF

  VendorGuid.Data1 = -1332766721;
  *&VendorGuid.Data2 = 1100211944;
  *VendorGuid.Data4 = -1637967959;
  *&VendorGuid.Data4[4] = 853215899;
  v2.Data1 = 1165015025;
  *&v2.Data2 = 1229172200;
  *v2.Data4 = 1681965965;
  *&v2.Data4[4] = -2078047118;
  v3.Data1 = -1426528487;
  *&v3.Data2 = 1083787512;
  *v3.Data4 = 1600452518;
  *&v3.Data4[4] = 1028417981;
  sub_1130(v6, 0, 0x77Fui64);
  v10 = 0;
  v11 = 0;
  v12 = 0;
  DataSize = 667i64;
  gRT->GetVariable(L"CpuSetup", &VendorGuid, &Attributes, &DataSize, Data);
  v5 = 256;
  gRT->SetVariable(L"CpuSetup", &VendorGuid, Attributes, DataSize, Data);
  DataSize = 1919i64;
  gRT->GetVariable(L"PchSetup", &v2, &Attributes, &DataSize, v6);
  v8 = 0;
  v7 = 0;
  gRT->SetVariable(L"PchSetup", &v2, Attributes, DataSize, v6);
  DataSize = 7i64;
  gRT->GetVariable(L"SiSetup", &v3, &Attributes, &DataSize, &v10);
  LOBYTE(v11) = 0;
  return gRT->SetVariable(L"SiSetup", &v3, Attributes, DataSize, &v10);
}

The gRT->SetVariable() service is called with the DataSize as an argument, which will be overwritten inside the gRT->GetVariable() service if the length of SiSetup NVRAM variable is greater than 7.

Thus, a potential attacker can dump X - 7 bytes from the stack (or global memory) into SiSetup NVRAM variable by setting SiSetup NVRAM variable's size to X > 7.

To fix this vulnerability the DataSize must be re-initialized with the size of SiSetup before calling gRT->SetVariable().

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)
Dell PSIRT is notified	2022-12-29
Dell PSIRT confirmed reported issue	2023-03-16
Dell PSIRT assigned CVE number	2023-06-15
Dell PSIRT provide patch release	2023-06-15
BINARLY public disclosure date	2023-06-21

Acknowledgements

BINARLY efiXplorer team

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BRLY-2022-159

Memory contents leak / information disclosure vulnerability in DXE driver on Dell platform.

Public Disclosure Date: Jun 21, 2023

CVE ID

CVE-2023-28060

Summary

Potential Impact

Vulnerability Information

BINARLY internal vulnerability identifier: BRLY-2022-159
Dell PSIRT assigned CVE identifier: CVE-2023-28060
DSA identifier: DSA-2023-099/DSA-2023-204
CVSS v3.1: 4.9 Medium AV:P/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Table of Contents

01.Affected Dell firmware

02.Vulnerability description

03.Disclosure timeline

04.Acknowledgements

Affected Dell firmware

Product	Firmware version	CPU	Module name	Module GUID	Module SHA256
Latitude 3120	0.1.13.1	AMD	9BCEDB6D-13CA-473E-B605-8A47688729FA	9bcedb6d-13ca-473e-b605-8a47688729fa	adc756cd7143c8c1ec9e1f776aa1c7cee49da09f6e02b5bc609bc6969d977dcb

Vulnerability description

Let's take Latitude 3120's firmware (version: 0.1.13.1, module sha256: adc756cd7143c8c1ec9e1f776aa1c7cee49da09f6e02b5bc609bc6969d977dcb) as an example.

The following code in the module actually allows leaking memory:

a call to a gRT->GetVariable() offset: 0xa65
a call to a gRT->SetVariable() offset: 0xa9c

EFI_STATUS __fastcall sub_8AC()
{
  EFI_GUID VendorGuid; // [rsp+30h] [rbp-D0h] BYREF
  EFI_GUID v2; // [rsp+40h] [rbp-C0h] BYREF
  EFI_GUID v3; // [rsp+50h] [rbp-B0h] BYREF
  char Data[226]; // [rsp+60h] [rbp-A0h] BYREF
  __int16 v5; // [rsp+142h] [rbp+42h]
  int v6[2]; // [rsp+300h] [rbp+200h] BYREF
  char v7; // [rsp+30Ah] [rbp+20Ah]
  char v8; // [rsp+930h] [rbp+830h]
  UINT32 Attributes; // [rsp+A90h] [rbp+990h] BYREF
  char v10; // [rsp+A98h] [rbp+998h] BYREF
  int v11; // [rsp+A99h] [rbp+999h]
  __int16 v12; // [rsp+A9Dh] [rbp+99Dh]
  UINTN DataSize; // [rsp+AA0h] [rbp+9A0h] BYREF

  VendorGuid.Data1 = -1332766721;
  *&VendorGuid.Data2 = 1100211944;
  *VendorGuid.Data4 = -1637967959;
  *&VendorGuid.Data4[4] = 853215899;
  v2.Data1 = 1165015025;
  *&v2.Data2 = 1229172200;
  *v2.Data4 = 1681965965;
  *&v2.Data4[4] = -2078047118;
  v3.Data1 = -1426528487;
  *&v3.Data2 = 1083787512;
  *v3.Data4 = 1600452518;
  *&v3.Data4[4] = 1028417981;
  sub_1130(v6, 0, 0x77Fui64);
  v10 = 0;
  v11 = 0;
  v12 = 0;
  DataSize = 667i64;
  gRT->GetVariable(L"CpuSetup", &VendorGuid, &Attributes, &DataSize, Data);
  v5 = 256;
  gRT->SetVariable(L"CpuSetup", &VendorGuid, Attributes, DataSize, Data);
  DataSize = 1919i64;
  gRT->GetVariable(L"PchSetup", &v2, &Attributes, &DataSize, v6);
  v8 = 0;
  v7 = 0;
  gRT->SetVariable(L"PchSetup", &v2, Attributes, DataSize, v6);
  DataSize = 7i64;
  gRT->GetVariable(L"SiSetup", &v3, &Attributes, &DataSize, &v10);
  LOBYTE(v11) = 0;
  return gRT->SetVariable(L"SiSetup", &v3, Attributes, DataSize, &v10);
}

Thus, a potential attacker can dump X - 7 bytes from the stack (or global memory) into SiSetup NVRAM variable by setting SiSetup NVRAM variable's size to X > 7.

To fix this vulnerability the DataSize must be re-initialized with the size of SiSetup before calling gRT->SetVariable().

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)
Dell PSIRT is notified	2022-12-29
Dell PSIRT confirmed reported issue	2023-03-16
Dell PSIRT assigned CVE number	2023-06-15
Dell PSIRT provide patch release	2023-06-15
BINARLY public disclosure date	2023-06-21

Acknowledgements

BINARLY efiXplorer team

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Potential Impact

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Vulnerability Information

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Affected Dell firmware

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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

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Vulnerability Information

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Affected Dell firmware

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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