Weakness · Medium
CWE-379: Creation of Temporary File in Directory with Insecure Permissions
What it is
The product creates a temporary file in a directory whose permissions allow unintended actors to determine the file's existence or otherwise access that file.
- Severity (our rating)
- Medium
- Likelihood of exploit
- Low
- Introduced during
- Implementation
- Exploited in the wild
- No CVE in CISA's catalog
In more detail
On some operating systems, the fact that the temporary file exists may be apparent to any user with sufficient privileges to access that directory. Since the file is visible, the application that is using the temporary file could be known. If one has access to list the processes on the system, the attacker has gained information about what the user is doing at that time. By correlating this with the applications the user is running, an attacker could potentially discover what a user's actions are. From this, higher levels of security could be breached.
What an attacker can do
- Read Application Data (Confidentiality)
How to prevent it
Requirements
- Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible.
Implementation
- Try to store sensitive tempfiles in a directory which is not world readable -- i.e., per-user directories.
- Avoid using vulnerable temp file functions.
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.