Weakness · Medium
CWE-526: Cleartext Storage of Sensitive Information in an Environment Variable
What it is
The product uses an environment variable to store unencrypted sensitive information.
- Severity (our rating)
- Medium
- Likelihood of exploit
- Not rated by MITRE
- Introduced during
- Architecture and Design, Implementation, Operation
- Exploited in the wild
- No CVE in CISA's catalog
In more detail
Information stored in an environment variable can be accessible by other processes with the execution context, including child processes that dependencies are executed in, or serverless functions in cloud environments. An environment variable's contents can also be inserted into messages, headers, log files, or other outputs. Often these other dependencies have no need to use the environment variable in question. A weakness that discloses environment variables could expose this information.
What an attacker can do
- Read Application Data (Confidentiality)
How to prevent it
Architecture and Design
- Encrypt information stored in the environment variable to protect it from being exposed to an unauthorized user. If encryption is not feasible or is considered too expensive for the business use of the application, then consider using a properly protected configuration file instead of an environment variable. It should be understood that unencrypted information in a config file is also not guaranteed to be protected, but it is still a better choice, because it reduces attack surface related to weaknesses such as CWE-214. In some settings, vaults might be a feasible option for safer data transfer. Users should be notified of the business choice made to not protect the sensitive information through encryption.
Implementation
- If the environment variable is not necessary for the desired behavior, then remove it entirely, or clear it to an empty value.
How to find it
- Automated Static Analysis. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
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Start freeSource: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.