A covert channel is a path that can be used to transfer information in a way not intended by the system's designers.
View on MITRETypically the system has not given authorization for the transmission and has no knowledge of its occurrence.
No mitigation information available for this CWE.
No detection method information available for this CWE.
In this example, the attacker observes how long an authentication takes when the user types in the correct password.
When the attacker tries their own values, they can first try strings of various length. When they find a string of the right length, the computation will take a bit longer, because the for loop will run at least once. Additionally, with this code, the attacker can possibly learn one character of the password at a time, because when they guess the first character right, the computation will take longer than a wrong guesses. Such an attack can break even the most sophisticated password with a few hundred guesses.
CWE-514: Covert Channel is a Common Weakness Enumeration (CWE) entry maintained by MITRE. A covert channel is a path that can be used to transfer information in a way not intended by the system's designers. Typically the system has not given authorization for the transmission and has no knowledge of its occurrence.
If exploited, CWE-514 (Covert Channel) it can compromise Confidentiality and Access Control, leading to outcomes such as Read Application Data and Bypass Protection Mechanism.
A CWE (Common Weakness Enumeration) like CWE-514 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.