CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
Home > CWE List > CWE- Individual Dictionary Definition (3.0)  
ID

CWE-379: Creation of Temporary File in Directory with Incorrect Permissions

Weakness ID: 379
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
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.
+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfBaseBase377Insecure Temporary File
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory376Temporary File Issues
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and Design
Implementation
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

(Language-Independent classes): (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Confidentiality

Technical Impact: Read Application Data

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

In the following code examples a temporary file is created and written to and after using the temporary file the file is closed and deleted from the file system.

(bad)
Example Language:
FILE *stream;
if( (stream = tmpfile()) == NULL ) {

perror("Could not open new temporary file\n");
return (-1);

}
// write data to tmp file

...
// remove tmp file
rmtmp();

However, within this C/C++ code the method tmpfile() is used to create and open the temp file. The tmpfile() method works the same way as the fopen() method would with read/write permission, allowing attackers to read potentially sensitive information contained in the temp file or modify the contents of the file.

(bad)
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) {
}

Similarly, the createTempFile() method used in the Java code creates a temp file that may be readable and writable to all users.

Additionally both methods used above place the file into a default directory. On UNIX systems the default directory is usually "/tmp" or "/var/tmp" and on Windows systems the default directory is usually "C:\\Windows\\Temp", which may be easily accessible to attackers, possibly enabling them to read and modify the contents of the temp file.

+ 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.
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
+ 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
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 9, "Temporary Files", Page 538.. 1st Edition. Addison Wesley. 2006.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
CLASP
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008-11-24CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2009-05-27CWE Content TeamMITRE
updated Description, Name
2009-07-27CWE Content TeamMITRE
updated Description, Other_Notes, Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2011-09-13CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2012-05-11CWE Content TeamMITRE
updated References, Relationships
2012-10-30CWE Content TeamMITRE
updated Demonstrative_Examples
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples, Taxonomy_Mappings
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

More information is available — Please select a different filter.
Page Last Updated: November 14, 2017