CWE-385: Covert Timing Channel

How it's found

Covert Timing Channel is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.

In some instances, knowing when data is transmitted between parties can provide a malicious user with privileged information. Also, externally monitoring the timing of operations can potentially reveal sensitive data. For example, a cryptographic operation can expose its internal state if the time it takes to perform the operation varies, based on the state. Covert channels are frequently classified as either storage or timing channels. Some examples of covert timing channels are the system's paging rate, the time a certain transaction requires to execute, and the time it takes to gain access to a shared bus.

Consequences

• Read Application Data, Other: Information exposure.

Mitigations

• Architecture and Design: Whenever possible, specify implementation strategies that do not introduce time variances in operations.
• Implementation: Often one can artificially manipulate the time which operations take or -- when operations occur -- can remove information from the attacker.
• Implementation: It is reasonable to add artificial or random delays so that the amount of CPU time consumed is independent of the action being taken by the application.

Where this fits in a TurboPentest engagement

This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.

Frequently asked questions

Related CWEs

• Class weakness
  CWE-514: Covert Channel