Description
The PHP application uses an old method for processing uploaded files by referencing the four global variables that are set for each file (e.g. $varname, $varname_size, $varname_name, $varname_type). These variables could be overwritten by attackers, causing the application to process unauthorized files.
These global variables could be overwritten by POST requests, cookies, or other methods of populating or overwriting these variables. This could be used to read or process arbitrary files by providing values such as “/etc/passwd”.
Modes of Introduction:
– Implementation
Related Weaknesses
Consequences
Confidentiality, Integrity: Read Files or Directories, Modify Files or Directories
Potential Mitigations
Phase: Architecture and Design
Description:
Use PHP 4 or later.
Phase: Architecture and Design
Description:
If you must support older PHP versions, write your own version of is_uploaded_file() and run it against $HTTP_POST_FILES[‘userfile’]))
Phase: Implementation
Description:
For later PHP versions, reference uploaded files using the $HTTP_POST_FILES or $_FILES variables, and use is_uploaded_file() or move_uploaded_file() to ensure that you are dealing with an uploaded file.
CVE References
- CVE-2002-1460
- Forum does not properly verify whether a file was uploaded or if the associated variables were set by POST, allowing remote attackers to read arbitrary files.
- CVE-2002-1759
- Product doesn’t check if the variables for an upload were set by uploading the file, or other methods such as $_POST.
- CVE-2002-1710
- Product does not distinguish uploaded file from other files.