CWE-1320: Improper Protection for Out of Bounds Signal Level Alerts
Untrusted agents can disable alerts about signal conditions exceeding limits or the response mechanism that handles such alerts.
Hardware sensors are used to detect whether a device is operating within design limits. The threshold values for these limits are set by hardware fuses or trusted software such as a BIOS. Modification of these limits may be protected by hardware mechanisms.
When device sensors detect out of bound conditions, alert signals may be generated for remedial action, which may take the form of device shutdown or throttling.
Warning signals that are not properly secured may be disabled or used to generate spurious alerts, causing degraded performance or denial-of-service (DoS). These alerts may be masked by untrusted software. Examples of these alerts involve thermal and power sensor alerts.
The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (CWE-1000)
Relevant to the view "Hardware Design" (CWE-1194)
The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
Class: Language-Independent (Undetermined Prevalence)
Class: OS-Independent (Undetermined Prevalence)
Class: Architecture-Independent (Undetermined Prevalence)
Class: System on Chip (Undetermined Prevalence)
Microcontroller IP (Undetermined Prevalence)
Memory IP (Undetermined Prevalence)
Power Management IP (Undetermined Prevalence)
Processor IP (Undetermined Prevalence)
Test/Debug IP (Undetermined Prevalence)
Sensor IP (Undetermined Prevalence)
The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Consider a platform design where a Digital-Thermal Sensor (DTS) is used to monitor temperature and compare that output against a threshold value. If the temperature output equals or exceeds the threshold value, the DTS unit sends an alert signal to the processor.
The processor, upon getting the alert, input triggers system shutdown. The alert signal is handled as a General-Purpose-I/O (GPIO) pin in input mode.
The processor-GPIO controller exposes software-programmable controls that allow untrusted software to reprogram the state of the GPIO pin.
Reprogramming the state of the GPIO pin allows malicious software to trigger spurious alerts or to set the alert pin to a zero value so that thermal sensor alerts are not received by the processor.
The GPIO alert-signal pin is blocked from untrusted software access and is controlled only by trusted software, such as the System BIOS.
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