GHSA-58xv-7h9r-mx3c
Drupal Malicious file upload with filenames stating with dot
Medium
Packagist
- Severity
- Medium
- The publisher's own rating, not a CVSS score
- Exploit chance (EPSS)
- —
- No score published
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-434 Unrestricted Upload of File with Dangerous Type
- Fix
8.7.11- Upgrade drupal/drupal to this version or later
Description
Drupal 8 core's file_save_upload() function does not strip the leading and trailing dot ('.') from filenames, like Drupal 7 did.
Users with the ability to upload files with any extension in conjunction with contributed modules may be able to use this to upload system files such as .htaccess in order to bypass protections afforded by Drupal's default .htaccess file.
After this fix, file_save_upload() now trims leading and trailing dots from filenames.
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| drupal/drupal | >= 8.0.0, < 8.7.11 |
8.7.11 |
| drupal/drupal | >= 8.8.0, < 8.8.1 |
8.8.1 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
drupal/drupal Packagist → 8.7.11
- composer
composer require drupal/drupal:^8.7.11
Weakness
CWE-434: Unrestricted Upload of File with Dangerous Type
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.
How to prevent it
- Architecture and Design: Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.[REF-422] [REF-423]
- Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- Architecture and Design: Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically. [REF-423]
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. For example, limiting filenames to alphanumeric characters can help to restrict the introduction of unintended file extensions.
- Architecture and Design: Define a very limited set of allowable extensions and only generate filenames that end in these extensions. Consider the possibility of XSS (CWE-79) before allowing .html or .htm file types.
- Implementation: Ensure that only one extension is used in the filename. Some web servers, including some versions of Apache, may process files based on inner extensions so that "filename.php.gif" is fed to the PHP interpreter.[REF-422] [REF-423]
- Implementation: When running on a web server that supports case-insensitive filenames, perform case-insensitive evaluations of the extensions that are provided.
- Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Implementation: Do not rely exclusively on sanity checks of file contents to ensure that the file is of the expected type and size. It may be possible for an attacker to hide code in some file segments that will still be executed by the server. For example, GIF images may contain a free-form comments field.
- Implementation: Do not rely exclusively on the MIME content type or filename attribute when determining how to render a file. Validating the MIME content type and ensuring that it matches the extension is only a partial solution.
- Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
- Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
References
Packages
Other links
Timeline
- Published
- Last updated by the source
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| CVE-2020-13671 Drupal core Unrestricted Upload of File with Dangerous Type | High Known exploited | Also affects drupal/drupal |
| CVE-2019-6340 Drupal Core Remote Code Execution Vulnerability | High Known exploited | Also affects drupal/drupal |
| CVE-2018-7602 Drupal Core Remote Code Execution Vulnerability | Critical Known exploited | Also affects drupal/drupal |
| CVE-2018-7600 Drupal Core Remote Code Execution Vulnerability | Critical Known exploited | Also affects drupal/drupal |
| DRUPAL-CORE-2024-008 Drupal core contains a potential PHP Object Injection vulnerability | Critical | Also affects drupal/drupal |
| DRUPAL-CORE-2024-007 Drupal core contains a potential PHP Object Injection vulnerability | Critical | Also affects drupal/drupal |
| DRUPAL-CORE-2024-006 Drupal core contains a potential PHP Object Injection vulnerability | Critical | Also affects drupal/drupal |
| DRUPAL-CORE-2024-004 Drupal core Access bypass | High | Also affects drupal/drupal |
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