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.
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.
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| ChildOf | Allowed-with-Review | C | 514 | Covert Channel |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 417 | Communication Channel Errors |
| MemberOf | Prohibited | C | 968 | SFP Secondary Cluster: Covert Channel |
| MemberOf | Prohibited | C | 1415 | Comprehensive Categorization: Resource Control |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | BS | BOSS-274 | High likelihood of exploit |
| MemberOf | Prohibited | BS | BOSS-328 | Read Application Data (impact) |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 417 | Communication Channel Errors |
| Nature | Mapping | Type | ID | Name |
|---|---|---|---|---|
| MemberOf | Prohibited | C | 968 | SFP Secondary Cluster: Covert Channel |
| Scope | Likelihood | Impact | Note |
|---|---|---|---|
| Confidentiality | N/A | Read Application Data | Covert storage channels may provide attackers with important information about the system in question. |
| IntegrityConfidentiality | N/A | 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. |
Covert storage channels may provide attackers with important information about the system in question.
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.
Ensure that all reserved fields are set to zero before messages are sent and that no unnecessary information is included.
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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.
| Reference | Description |
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| Ordinality | Description |
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This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
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.
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| Taxonomy Name | Entry ID | Fit | Entry Name |
|---|---|---|---|
| Landwehr | N/A | N/A | Storage |
| CLASP | N/A | N/A | Covert storage channel |
| ID | Name |
|---|