CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-515: Covert Storage Channel

Weakness ID: 515
Abstraction: Base
Status: Incomplete
Presentation Filter:
+ Description

Description Summary

A covert storage channel transfers information through the setting of bits by one program and the reading of those bits by another. What distinguishes this case from that of ordinary operation is that the bits are used to convey encoded information.

Extended Description

Covert storage channels occur when out-of-band data is stored in messages for the purpose of memory reuse. Covert channels are frequently classified as either storage or timing channels. Examples would include using a file intended to hold only audit information to convey user passwords--using the name of a file or perhaps status bits associated with it that can be read by all users to signal the contents of the file. Steganography, concealing information in such a manner that no one but the intended recipient knows of the existence of the message, is a good example of a covert storage channel.

+ Time of Introduction
  • Implementation
+ Common Consequences
ScopeEffect
Confidentiality

Technical Impact: Read application data

Covert storage channels may provide attackers with important information about the system in question.

Integrity
Confidentiality

Technical Impact: Read application data

If these messages or packets are sent with unnecessary data contained within, it may tip off malicious listeners as to the process that created the message. With this information, attackers may learn any number of things, including the hardware platform, operating system, or algorithms used by the sender. This information can be of significant value to the user in launching further attacks.

+ Likelihood of Exploit

High

+ Demonstrative Examples

Example 1

An excellent example of covert storage channels in a well known application is the ICMP error message echoing functionality. Due to ambiguities in the ICMP RFC, many IP implementations use the memory within the packet for storage or calculation. For this reason, certain fields of certain packets -- such as ICMP error packets which echo back parts of received messages -- may contain flaws or extra information which betrays information about the identity of the target operating system. This information is then used to build up evidence to decide the environment of the target. This is the first crucial step in determining if a given system is vulnerable to a particular flaw and what changes must be made to malicious code to mount a successful attack.

+ Potential Mitigations

Phase: Implementation

Ensure that all reserved fields are set to zero before messages are sent and that no unnecessary information is included.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class514Covert Channel
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory968SFP Secondary Cluster: Covert Channel
Software Fault Pattern (SFP) Clusters (primary)888
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
LandwehrStorage
CLASPCovert storage channel
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
LandwehrExternally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time_of_Introduction
2008-09-08CWE Content TeamMITREInternal
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008-10-14CWE Content TeamMITREInternal
updated Description
2009-07-27CWE Content TeamMITREInternal
updated Common_Consequences, Description
2009-10-29CWE Content TeamMITREInternal
updated Other_Notes
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences
2012-05-11CWE Content TeamMITREInternal
updated Relationships
2014-07-30CWE Content TeamMITREInternal
updated Relationships

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Page Last Updated: January 18, 2017