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Weakness · High

CWE-378: Creation of Temporary File With Insecure Permissions

What it is

Opening temporary files without appropriate measures or controls can leave the file, its contents and any function that it impacts vulnerable to attack.

Likelihood of exploit: HighMITRE CWE 4.19.1

Severity (our rating)
High
Likelihood of exploit
High
Introduced during
Implementation
Exploited in the wild
No CVE in CISA's catalog

What an attacker can do

  • Read Application Data (Confidentiality)
  • Other (Authorization, Other, Integrity)

How to prevent it

Requirements

  • Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible.

Implementation

  • Ensure that you use proper file permissions. This can be achieved by using a safe temp file function. Temporary files should be writable and readable only by the process that owns the file.
  • Randomize temporary file names. This can also be achieved by using a safe temp-file function. This will ensure that temporary files will not be created in predictable places.

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.)

CWE-378 on MITRE's CWE site

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Source: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.