Sensitive Information Accessible by Physical Probing of JTAG Interface

Sensitive information in clear text on the JTAG interface may be examined by an eavesdropper, e.g. by placing a probe device on the interface such as a logic analyzer, or a corresponding software technique.


On a debug configuration with a remote host, unbeknownst to the host/user, an attacker with physical access to a target system places a probing device on the debug interface or software related to the JTAG port e.g. device driver. While the authorized host/user performs sensitive operations to the target system, the attacker uses the probe to collect the JTAG traffic.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

A TAP accessible register is read/written by a JTAG based tool, for internal tool use for an authorized user. The JTAG based tool does not provide access to this data to an unauthorized user of the tool. However, the user can connect a probing device and collect the values directly from the JTAG interface, if no additional protections are employed.

See Also

Debug and Test Problems

Weaknesses in this category are related to hardware debug and test interfaces such as JTAG and scan chain.

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses without Software Fault Patterns

CWE identifiers in this view are weaknesses that do not have associated Software Fault Patterns (SFPs), as covered by the CWE-888 view. As such, they represent gaps in...

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

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