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CWE-378 Individual Dictionary Definition (Draft 9)
Weakness ID
| Status: Draft 378 (Weakness Base) | | 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. | | Likelihood of Exploit | High | | Common Consequences | Confidentiality: If the temporary file can be read, by the attacker, sensitive
information may be in that file which could be revealed. Authorization: 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. | | 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. 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. 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. | Demonstrative
Examples | C/C++ Example: 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(); The temp file created in the above code is always readable and writable
by all users. Java Example: 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. | | Context Notes | 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. | | Relationships | | | Source Taxonomies | CLASP - Improper temp file opening | | Applicable Platforms | All |
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- Weakness
- Base
- Variant
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- Composite
- Category
- View
- Deprecated
