Covert channels are a type of communication link where data is transferred using methods not originally intended for communication. This hidden communication often exploits legitimate channels to relay information secretly, bypassing usual data transfer protocols. These channels are often used for malicious purposes, such as leaking sensitive data without detection.
Covert Channels Examples
1. Timing Information
In a typical computer system, multiple process tasks can be executed simultaneously. Each process would, most likely, have a specific role or function. For example, imagine a scenario where there are two processes, the first of which contains sensitive data and the second is a seemingly harmless application. Now, consider that these two processes are covertly linked.
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The first process, instead of directly transferring data to the second one, alters its operation timing based on the data it wants to transfer. For instance, it may select to operate slowly for binary 0 and faster for binary 1. By simply observing the process operations, the second process can decode the message since it is privy to the time-sensitive code. The slower and faster-paced executions are used to pass on binary data covertly.
This way, sensitive information is communicated secretly through a legitimately running process’s operation duration. The alarming factor is that this can occur under the radar of most security systems since they’re not designed to track such time-based manipulations.
2. Hidden Internet Traffic
Another example of a covert channel is hidden internet traffic. This occurs when an attacker uses approved or “safe” network passage to hide the unauthorized communication. The data transfer happens through a legitimate sequence of actions, making it hard to detect.
An instance of this could be an attacker using the traffic pattern of a known website to send a secret message. For example, they might use the timing or sequence of visiting particular pages on this website to encode the data they want to transfer. To an observer or security system, this might look like ordinary user behavior.
Given that this covert channel is disguised as normal web usage, it can easily bypass security checks and network monitoring tools. Thorough network traffic analysis is required to identify and prevent such covert communication.
3. Metadata in Files
A covert channel could also be established using the metadata within files. Metadata usually provides descriptions, timestamps, and other basic information about a file. This is often overlooked because it’s part of standard file operations.
Now consider a scenario where an attacker inserts extra information in the form of covert data within the metadata of a larger and seemingly harmless file. Everything appears normal from the outside, and the added data might go unnoticed in a normal security screening.
Since the file appears to be ordinary, it could even be transferred outside the network boundaries without raising any alerts. This would enable the covert channel – disguised within the file metadata – to transmit sensitive data unnoticed. Recognizing and blocking such covert channels requires diligent and meticulous security checks.
Conclusion
Covert channels represent a significant threat in the field of cybersecurity, providing secretive communication links masked within ordinary actions or data. Understanding and detecting these hidden communication channels require meticulous and thorough security practices to prevent unauthorized data leakage.
Key Takeaways
- Covert channels are secret communication links used to transfer data undetected.
- These channels exploit ordinary actions or data processes, making them hard to detect.
- Examples include manipulating process timing, hiding data in normal internet traffic, and embedding data within file metadata.
- Covert channels represent a sizable threat in cybersecurity, often used for unauthorized transmission of sensitive data.
- Identifying and blocking covert channels require advanced, multi-layered security checks.
Related Questions
1. How does one mitigate the risk of covert channels?
To mitigate the risk of covert channels, it requires robust and comprehensive security measures. Regular comprehensive system audits, advanced data leakage prevention tools, egress filtering, and traffic pattern analysis can all be useful in detecting and blocking such channels.
2. How does embedding data within file metadata constitute a covert channel?
A covert channel can be created in file metadata by secretly embedding extra information. As metadata belongs to standard file operations, it frequently bypasses security checks. If an attacker inserts covert data within the metadata of a seemingly benign file, it can transfer sensitive information unnoticed.
3. Can you explain more about the timing information covert channel?
An example of a timing information covert channel is where one process alters its operation timing to indirectly transfer data to another process. An observer to the timing changes can interpret these as a data stream making this a covert communication channel.
4. Why is it challenging to detect hidden internet traffic as a covert channel?
Hidden internet traffic as a covert channel can be difficult to detect as the communication is disguised within legitimate web activities. The traffic patterns of a trusted website could be used to transmit data, and to a casual observer or security system, this might appear as typical internet usage.
5. How can covert channels be harmful to an organization?
Covert channels can be harmful as they can allow unauthorized communication bypassing typical data transfer protocols. They can be used to secretly send out sensitive information or signals which can lead to data breaches, intellectual property theft, or enable further infiltration into the system.
"Amateurs hack systems, professionals hack people."
-- Bruce Schneier, a renown computer security professional
