Creation of Temporary File in Directory with Incorrect Permissions
Weakness ID: 379 (Weakness Base)Status: Incomplete
+ Description

Description Summary

The software creates a temporary file in a directory whose permissions allow unintended actors to determine the file's existence or otherwise access that file.

Extended Description

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.

+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms

Languages

All

+ Common Consequences
ScopeEffect
Confidentiality

Since the file is visible and the application which is using the temp file could be known, the attacker has gained information about what the user is doing at that time.

+ Likelihood of Exploit

Low

+ 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 */
/* ... */
_rmtmp();

In cygwin and some older unixes one can ls /tmp and see that this temp file exists.

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

This temp file is readable by all users.

+ Potential Mitigations

Phase: Requirements

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

Phase: Implementation

Try to store sensitive tempfiles in a directory which is not world readable -- i.e., per-user directories.

Phase: Implementation

Avoid using vulnerable temp file functions.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfCategoryCategory376Temporary File Issues
Development Concepts (primary)699
ChildOfWeakness BaseWeakness Base377Insecure Temporary File
Research Concepts (primary)1000
ChildOfCategoryCategory743CERT C Secure Coding Section 09 - Input Output (FIO)
Weaknesses Addressed by the CERT C Secure Coding Standard (primary)734
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPGuessed or visible temporary file
CERT C Secure CodingFIO15-CEnsure that file operations are performed in a secure directory
CERT C Secure CodingFIO43-CDo not create temporary files in shared directories
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
CLASPExternally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Common Consequences, Relationships, Other Notes, Taxonomy Mappings
2008-11-24CWE Content TeamMITREInternal
updated Relationships, Taxonomy Mappings
2009-05-27CWE Content TeamMITREInternal
updated Description, Name
2009-07-27CWE Content TeamMITREInternal
updated Description, Other Notes, Potential Mitigations
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Guessed or Visible Temporary File
2009-05-27Creation of Temporary File in Directory with Insecure Permissions
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