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CVE-2023-41330

Estado: ModificadaCrítica (9.8)—

knplabs/knp-snappy is a PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page. ## Issue

On March 17th the vulnerability CVE-2023-28115 was disclosed, allowing an attacker to gain remote code execution through PHAR deserialization. Version 1.4.2 added a check `if (\strpos($filename, 'phar://') === 0)` in the `prepareOutput` function to resolve this CVE, however if the user is able to control the second parameter of the `generateFromHtml()` function of Snappy, it will then be passed as the `$filename` parameter in the `prepareOutput()` function.

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In the original vulnerability, a file name with a `phar://` wrapper could be sent to the `fileExists()` function, equivalent to the `file_exists()` PHP function. This allowed users to trigger a deserialization on arbitrary PHAR files. To fix this issue, the string is now passed to the `strpos()` function and if it starts with `phar://`, an exception is raised. However, PHP wrappers being case insensitive, this patch can be bypassed using `PHAR://` instead of `phar://`. A successful exploitation of this vulnerability allows executing arbitrary code and accessing the underlying filesystem. The attacker must be able to upload a file and the server must be running a PHP version prior to 8. This issue has been addressed in commit `d3b742d61a` which has been included in version 1.4.3. Users are advised to upgrade. Users unable to upgrade should ensure that only trusted users may submit data to the `AbstractGenerator->generate(...)` function.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Knplabs — Snappy

CWE

Referencias

JSON original (NVD)

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      "value": "knplabs/knp-snappy is a PHP library allowing thumbnail, snapshot or PDF generation from a url or a html page.\n## Issue\n\nOn March 17th the vulnerability CVE-2023-28115 was disclosed, allowing an attacker to gain remote code execution through PHAR deserialization. Version 1.4.2 added a check `if (\\strpos($filename, 'phar://') === 0)` in the `prepareOutput` function to resolve this CVE, however if the user is able to control the second parameter of the `generateFromHtml()` function of Snappy, it will then be passed as the `$filename` parameter in the `prepareOutput()` function. In the original vulnerability, a file name with a `phar://` wrapper could be sent to the `fileExists()` function, equivalent to the `file_exists()` PHP function. This allowed users to trigger a deserialization on arbitrary PHAR files. To fix this issue, the string is now passed to the `strpos()` function and if it starts with `phar://`, an exception is raised. However, PHP wrappers being case insensitive, this patch can be bypassed using `PHAR://` instead of `phar://`. A successful exploitation of this vulnerability allows executing arbitrary code and accessing the underlying filesystem. The attacker must be able to upload a file and the server must be running a PHP version prior to 8. This issue has been addressed in commit `d3b742d61a` which has been included in version 1.4.3. Users are advised to upgrade. Users unable to upgrade should ensure that only trusted users may submit data to the `AbstractGenerator->generate(...)` function.\n"
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      "value": "knplabs/knp-snappy es una librería PHP que permite la generación de thumbnail, snapshots o PDFs desde una URL o una página HTML. ## El problema que reveló la vulnerabilidad CVE-2023-28115 el 17 de marzo, permite a un atacante obtener la ejecución remota de código mediante la deserialización PHAR. La versión 1.4.2 agregó una verificación `if (\\strpos($filename, 'phar://') === 0)` en la función `prepareOutput` para resolver este CVE, sin embargo, si el usuario puede controlar el segundo parámetro de la función `generateFromHtml()` de Snappy, luego se pasará como el parámetro `$filename` en la función `prepareOutput()`. En la vulnerabilidad original, un nombre de archivo con un contenedor `phar://` podría enviarse a la función `fileExists()`, equivalente a la función PHP `file_exists()`. Esto permitió a los usuarios activar una deserialización en archivos PHAR arbitrarios. Para solucionar este problema, la cadena ahora se pasa a la función `strpos()` y si comienza con `phar://`, se genera una excepción. Sin embargo, como los contenedores de PHP no distinguen entre mayúsculas y minúsculas, este parche se puede omitir usando `PHAR://` en lugar de `phar://`. Una explotación exitosa de esta vulnerabilidad permite ejecutar código arbitrario y acceder al sistema de archivos subyacente. El atacante debe poder cargar un archivo y el servidor debe ejecutar una versión de PHP anterior a la 8. Este problema se solucionó en el commit `d3b742d61a` que se incluyó en la versión 1.4.3. Se recomienda a los usuarios que actualicen. Los usuarios que no puedan actualizar deben asegurarse de que solo los usuarios confiables puedan enviar datos a la función `AbstractGenerator-&gt;generate(...)`."
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