COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONMITRE canlı kaydı

CAPEC-702

Exploiting Incorrect Chaining or Granularity of Hardware Debug Components

An adversary exploits incorrect chaining or granularity of hardware debug components in order to gain unauthorized access to debug functionality on a chip. This happens when authorization is not checked on a per function basis and is assumed for a chain or group of debug functionality.

Soyutlama

Detailed

Tipik ciddiyet

Medium

Saldırı ihtimali

Low

Saldırıyı anla

Bu saldırı kalıbı nedir?

An adversary exploits incorrect chaining or granularity of hardware debug components in order to gain unauthorized access to debug functionality on a chip. This happens when authorization is not checked on a per function basis and is assumed for a chain or group of debug functionality.

Genişletilmiş açıklama

Chip designers often include design elements in a chip for debugging and troubleshooting such as: Various Test Access Ports (TAPs) which allow boundary scan commands to be executed. Scan cells that allow the chip to be used as a "stimulus and response" mechanism for scanning the internal components of a chip. Custom methods to observe the internal components of their chips by placing various tracing hubs within their chip and creating hierarchical or interconnected structures among those hubs. Because devices commonly have multiple chips and debug components, designers will connect debug components and expose them through a single external interface, which is referred to as “chaining”. Logic errors during design or synthesis could misconfigure the chaining of the debug components, which could allow unintended access. TAPs are also commonly referred to as JTAG interfaces.

Uygulama akışı

Saldırı adım adım nasıl ilerler?

1

Explore

Find and scan debug interface

The adversary must first find and scan a debug interface to determine what they are authorized to use and what devices are chained to that interface.

Kullanılan teknikler

  • Use a JTAGulator on a JTAG interface to determine the correct pin configuration, baud rate, and number of devices in the chain
2

Experiment

Connect to debug interface

The adversary next connects a device to the JTAG interface using the properties found in the explore phase so that they can send commands. The adversary sends some test commands to make sure the connection is working.

Kullanılan teknikler

  • Connect a device such as a BusPirate or UM232H to the JTAG interface and connect using pin layout found from the JTAGulator
3

Exploit

Move along debug chain

Once the adversary has connected to the main TAP, or JTAG interface, they will move along the TAP chain to see what debug interfaces might be available on that chain.

Kullanılan teknikler

  • Run a command such as “scan_chain” to see what TAPs are available in the chain.

Gereksinimler

Saldırının gerçekleşmesi için ne gerekir?

Ön koşullar

  • Hardware device has an exposed debug interface

Gerekli beceri

  • Medium: Ability to identify physical debug interfaces on a device
  • Medium: Ability to operate devices to scan and connect to an exposed debug interface

Gerekli kaynak

  • A device to scan a TAP or JTAG interface, such as a JTAGulator
  • A device to communicate on a TAP or JTAG interface, such as a BusPirate

Etki

Başarılı saldırı neye yol açar?

Read Data

Etkilenen alanlar: Confidentiality

Modify Data

Etkilenen alanlar: Integrity

Gain Privileges

Etkilenen alanlar: Access Control, Authorization

Savunma

Nasıl önlenir ve etkisi azaltılır?

1
Implement: Ensure that debug components are properly chained, and their granularity is maintained at different authorization levels
2
Perform Post-silicon validation tests at various authorization levels to ensure that debug components are only accessible to authorized users

Gerçek dünya

MITRE örnek olayları

Örnek olay 1Detay
A System-on-Chip (SoC) might give regular users access to the SoC-level TAP, but does not want to give access to all of the internal TAPs (e.g., Core). If any of the internal TAPs were incorrectly chained to the SoC-level TAP, this would grant regular users access to the internal TAPs and allow them to execute commands there.
Örnek olay 2Detay
Suppose there is a hierarchy of TAPs (TAP_A is connected to TAP_B and TAP_C, then TAP_B is connected to TAP_D and TAP_E, then TAP_C is connected to TAP_F and TAP_G, etc.). Architecture mandates that the user have one set of credentials for just accessing TAP_A, another set of credentials for accessing TAP_B and TAP_C, etc. However, if, during implementation, the designer mistakenly implements a daisy-chained TAP where all the TAPs are connected in a single TAP chain without the hierarchical structure, the correct granularity of debug components is not implemented, and the attacker can gain unauthorized access.
CAPEC-702: Exploiting Incorrect Chaining or Granularity of Hardware Debug Components — DayBreach Saldırı Sözlüğü · DayBreach