Creation of Temporary File With Insecure Permissions
Weakness ID: 378 (Weakness Base)Status: Draft
+ Description

Description Summary

Opening temporary files without appropriate measures or controls can leave the file, its contents and any function that it impacts vulnerable to attack.
+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms



+ Common Consequences

If the temporary file can be read, by the attacker, sensitive information may be in that file which could be revealed.


If that file can be written to by the attacker, the file might be moved into a place to which the attacker does not have access. This will allow the attacker to gain selective resource access-control privileges.


Depending on the data stored in the temporary file, there is the potential for an attacker to gain an additional input vector which is trusted as non-malicious. It may be possible to make arbitrary changes to data structures, user information, or even process ownership.

+ Likelihood of Exploit


+ Demonstrative Examples

Example 1

(Bad Code)
Example Languages: C and C++ 
FILE *stream; char tempstring[] = "String to be written";
if( (stream = tmpfile()) == NULL ) {

perror("Could not open new temporary file\n");
return (-1);
/* write data to tmp file */
/* ... */

The temp file created in the above code is always readable and writable by all users.

(Bad Code)
Example Language: Java 
try {
File temp = File.createTempFile("pattern", ".suffix");
BufferedWriter out = new BufferedWriter(new FileWriter(temp));
catch (IOException e) {


This temp file is readable by all users.

+ Potential Mitigations

Tempfile creation should be done in a safe way. To be safe, the temp file function should open up the temp file with appropriate access control. The temp file function should also retain this quality, while being resistant to race conditions.

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

Phase: 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 which own the file.

Phase: Implementation

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.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfCategoryCategory376Temporary File Issues
Development Concepts (primary)699
ChildOfWeakness BaseWeakness Base377Insecure Temporary File
Research Concepts (primary)1000
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPImproper temp file opening
+ Content History
Submission DateSubmitterOrganizationSource
CLASPExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Common Consequences, Relationships, Other Notes, Taxonomy Mappings
2009-10-29CWE Content TeamMITREInternal
updated Common Consequences, Other Notes
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Improper Temporary File Opening