Covert Timing Channel

Opis

Covert timing channels convey information by modulating some aspect of system behavior over time, so that the program receiving the information can observe system behavior and infer protected information.

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.

Skutki

• Confidentiality, Other

  Read Application Data; Other

  Information exposure.

Zapobieganie

• 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.

Słabość nadrzędna

• CWE-514 Covert Channel

Kiedy powstaje

• Architecture and Design
• Implementation

Dotyczy

Not Language-Specific

Uwagi

As of CWE 4.9, members of the CWE Hardware SIG are working to improve CWE's coverage of transient execution weaknesses, which include issues related to Spectre, Meltdown, and other attacks that create or exploit covert channels. As a result of that work, this entry might change in CWE 4.10.

Źródła

1. The CLASP Application Security Process — Secure Software, Inc., 2005
2. A Taxonomy of Computer Program Security Flaws, with Examples — Carl E. Landwehr, Alan R. Bull, John P. McDermott, William S. Choi, 1993