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.
6008 vulnerabilities reference this CWE, most recent first.
GHSA-82HF-RJV3-P249
Vulnerability from github – Published: 2024-05-16 06:30 – Updated: 2025-02-10 15:32A vulnerability was found in SourceCodester Best Courier Management System 1.0. It has been classified as problematic. Affected is an unknown function of the file view_parcel.php. The manipulation of the argument id leads to unrestricted upload. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-264480.
{
"affected": [],
"aliases": [
"CVE-2024-4945"
],
"database_specific": {
"cwe_ids": [
"CWE-434",
"CWE-89"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-16T05:15:52Z",
"severity": "MODERATE"
},
"details": "A vulnerability was found in SourceCodester Best Courier Management System 1.0. It has been classified as problematic. Affected is an unknown function of the file view_parcel.php. The manipulation of the argument id leads to unrestricted upload. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used. The identifier of this vulnerability is VDB-264480.",
"id": "GHSA-82hf-rjv3-p249",
"modified": "2025-02-10T15:32:11Z",
"published": "2024-05-16T06:30:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-4945"
},
{
"type": "WEB",
"url": "https://github.com/CveSecLook/cve/issues/28"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.264480"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.264480"
},
{
"type": "WEB",
"url": "https://vuldb.com/?submit.333960"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/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-82QP-XCGQ-F3C5
Vulnerability from github – Published: 2023-09-25 18:30 – Updated: 2024-04-04 07:50The Prevent files / folders access WordPress plugin before 2.5.2 does not validate files to be uploaded, which could allow attackers to upload arbitrary files such as PHP on the server.
{
"affected": [],
"aliases": [
"CVE-2023-4238"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-09-25T16:15:14Z",
"severity": "HIGH"
},
"details": "The Prevent files / folders access WordPress plugin before 2.5.2 does not validate files to be uploaded, which could allow attackers to upload arbitrary files such as PHP on the server.",
"id": "GHSA-82qp-xcgq-f3c5",
"modified": "2024-04-04T07:50:33Z",
"published": "2023-09-25T18:30:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-4238"
},
{
"type": "WEB",
"url": "https://wpscan.com/vulnerability/53816136-4b1a-4b7d-b73b-08a90c2a638f"
}
],
"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-82RC-GXRG-V4GF
Vulnerability from github – Published: 2026-05-19 16:31 – Updated: 2026-06-08 23:51Summary
The file upload endpoint POST /api/attachments/process does not enforce active-content restrictions for authenticated users. The checks for dangerous file extensions (html, svg, js, php, etc.) are conditionally wrapped inside if (isPublicUser) or if (isPublicUser || !env.SELF_HOSTED), meaning any authenticated builder can upload executable web content — SVG files with inline <script> tags, HTML pages with JavaScript, .js modules — which are then stored in the object store (MinIO/S3) with their correct MIME types (image/svg+xml, text/html, application/javascript). When the resulting signed URL is opened by any app user, the browser executes the payload.
Impact is persistent stored XSS over all application end users.
Details
The vulnerability exists in a single handler function uploadFile shared by two routes, located in packages/server/src/api/controllers/static/index.ts (lines 93–179).
Route definitions (packages/server/src/api/routes/static.ts):
POST /api/attachments/process → authorized(BUILDER) POST /api/attachments/:tableId/upload → authorized(PermissionType.TABLE, PermissionLevel.WRITE) Both routes invoke the same uploadFile function. The second endpoint is accessible to any authenticated app user (BASIC or POWER role) who has been granted WRITE on any table — not just builders.
PoC
Prerequisites
- Budibase self-hosted Docker deployment, any version ≤ 3.30.6
- An account with Builder role (does not require admin)
- Target app published and accessible to end users
Step 1 — Authenticate as builder
POST /api/global/auth/default/login HTTP/1.1
Host: target:10000
Content-Type: application/json
{"username":"builder@company.com","password":"BuilderPass1!"}
HTTP/1.1 200 OK
Set-Cookie: budibase:auth=<jwt>; path=/; expires=Tue, 19 Jan 2038 03:14:07 GMT
Set-Cookie: budibase:auth.sig=<sig>; path=/; expires=Tue, 19 Jan 2038 03:14:07 GMT
{"message":"Login successful"}
The CSRF token is bound to the session. Browsers send it automatically via the Budibase
frontend JS. For scripted requests, decode the JWT payload (base64url second segment) to
extract sessionId, then read the Redis key session-<userId>/<sessionId> → csrfToken.
Step 2 — Upload SVG with XSS payload
POST /api/attachments/process HTTP/1.1
Host: target:10000
Cookie: budibase:auth=<jwt>; budibase:auth.sig=<sig>
x-budibase-app-id: <dev_app_id>
x-csrf-token: <csrf_token>
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryXXXXXXXXXXXXXXXX
Content-Length: 391
------WebKitFormBoundaryXXXXXXXXXXXXXXXX
Content-Disposition: form-data; name="file"; filename="xss.svg"
Content-Type: image/svg+xml
<svg xmlns="http://www.w3.org/2000/svg"><script>alert(document.domain)</script></svg>
------WebKitFormBoundaryXXXXXXXXXXXXXXXX--
HTTP/1.1 200 OK
[{"size":207,"name":"xss.svg","url":"http://target:10000/files/signed/.../<uuid>.svg?X-Amz-...","extension":"svg","key":"workspace_id/attachments/<uuid>.svg"}]
Impact
- App end users - Stored XSS on any screen containing the attachment URL. Session cookie theft → full account takeover. |
- Builder accounts - If malicious URL is shared within the workspace (table attachment, embedded image), XSS fires in builder's session → workspace takeover.
Discovered By: Abdulrahman Albatel Abdullah Alrasheed
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "budibase"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.38.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-46426"
],
"database_specific": {
"cwe_ids": [
"CWE-434",
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-19T16:31:30Z",
"nvd_published_at": "2026-05-27T18:16:26Z",
"severity": "HIGH"
},
"details": "### Summary\nThe file upload endpoint `POST /api/attachments/process` does not enforce active-content restrictions for authenticated users. The checks for dangerous file extensions (`html`, `svg`, `js`, `php`, etc.) are conditionally wrapped inside `if (isPublicUser)` or `if (isPublicUser || !env.SELF_HOSTED)`, meaning any authenticated builder can upload executable web content \u2014 SVG files with inline `\u003cscript\u003e` tags, HTML pages with JavaScript, `.js` modules \u2014 which are then stored in the object store (MinIO/S3) with their correct MIME types (`image/svg+xml`, `text/html`, `application/javascript`). When the resulting signed URL is opened by any app user, the browser executes the payload.\n\nImpact is **persistent stored XSS** over all application end users.\n\n### Details\nThe vulnerability exists in a single handler function uploadFile shared by two routes, located in packages/server/src/api/controllers/static/index.ts (lines 93\u2013179).\n\nRoute definitions (packages/server/src/api/routes/static.ts):\n\nPOST /api/attachments/process \u2192 authorized(BUILDER)\nPOST /api/attachments/:tableId/upload \u2192 authorized(PermissionType.TABLE, PermissionLevel.WRITE)\nBoth routes invoke the same uploadFile function. The second endpoint is accessible to any authenticated app user (BASIC or POWER role) who has been granted WRITE on any table \u2014 not just builders.\n\n### PoC\n\n### Prerequisites\n\n- Budibase self-hosted Docker deployment, any version \u2264 3.30.6\n- An account with Builder role (does **not** require admin)\n- Target app published and accessible to end users\n\n### Step 1 \u2014 Authenticate as builder\n\n```http\nPOST /api/global/auth/default/login HTTP/1.1\nHost: target:10000\nContent-Type: application/json\n\n{\"username\":\"builder@company.com\",\"password\":\"BuilderPass1!\"}\n```\n\n```\nHTTP/1.1 200 OK\nSet-Cookie: budibase:auth=\u003cjwt\u003e; path=/; expires=Tue, 19 Jan 2038 03:14:07 GMT\nSet-Cookie: budibase:auth.sig=\u003csig\u003e; path=/; expires=Tue, 19 Jan 2038 03:14:07 GMT\n\n{\"message\":\"Login successful\"}\n```\n\nThe CSRF token is bound to the session. Browsers send it automatically via the Budibase\nfrontend JS. For scripted requests, decode the JWT payload (base64url second segment) to\nextract `sessionId`, then read the Redis key `session-\u003cuserId\u003e/\u003csessionId\u003e` \u2192 `csrfToken`.\n\n### Step 2 \u2014 Upload SVG with XSS payload\n\n```http\nPOST /api/attachments/process HTTP/1.1\nHost: target:10000\nCookie: budibase:auth=\u003cjwt\u003e; budibase:auth.sig=\u003csig\u003e\nx-budibase-app-id: \u003cdev_app_id\u003e\nx-csrf-token: \u003ccsrf_token\u003e\nContent-Type: multipart/form-data; boundary=----WebKitFormBoundaryXXXXXXXXXXXXXXXX\nContent-Length: 391\n\n------WebKitFormBoundaryXXXXXXXXXXXXXXXX\nContent-Disposition: form-data; name=\"file\"; filename=\"xss.svg\"\nContent-Type: image/svg+xml\n\n\u003csvg xmlns=\"http://www.w3.org/2000/svg\"\u003e\u003cscript\u003ealert(document.domain)\u003c/script\u003e\u003c/svg\u003e\n------WebKitFormBoundaryXXXXXXXXXXXXXXXX--\n```\n\n```json\nHTTP/1.1 200 OK\n\n[{\"size\":207,\"name\":\"xss.svg\",\"url\":\"http://target:10000/files/signed/.../\u003cuuid\u003e.svg?X-Amz-...\",\"extension\":\"svg\",\"key\":\"workspace_id/attachments/\u003cuuid\u003e.svg\"}]\n```\n### Impact\n* App end users - Stored XSS on any screen containing the attachment URL. Session cookie theft \u2192 full account takeover. |\n* Builder accounts - If malicious URL is shared within the workspace (table attachment, embedded image), XSS fires in builder\u0027s session \u2192 workspace takeover. \n\n\n\u003cimg width=\"3087\" height=\"1489\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b0ee0263-85de-430e-9575-88ec91eae565\" /\u003e\n\n\n\u003cimg width=\"2100\" height=\"1016\" alt=\"image\" src=\"https://github.com/user-attachments/assets/5133bb1e-f637-479e-952f-14b3265129b4\" /\u003e\n\n\n\n\n\n\n\n--------\nDiscovered By:\nAbdulrahman Albatel\nAbdullah Alrasheed",
"id": "GHSA-82rc-gxrg-v4gf",
"modified": "2026-06-08T23:51:56Z",
"published": "2026-05-19T16:31:30Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Budibase/budibase/security/advisories/GHSA-82rc-gxrg-v4gf"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46426"
},
{
"type": "PACKAGE",
"url": "https://github.com/Budibase/budibase"
},
{
"type": "WEB",
"url": "https://github.com/Budibase/budibase/releases/tag/3.38.2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Budibase: Unrestricted Upload of File with Dangerous Type"
}
GHSA-835W-28HJ-65XX
Vulnerability from github – Published: 2022-10-29 12:00 – Updated: 2022-11-01 19:00wasm2c v1.0.29 was discovered to contain an abort in CWriter::Write.
{
"affected": [],
"aliases": [
"CVE-2022-43283"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-10-28T21:15:00Z",
"severity": "MODERATE"
},
"details": "wasm2c v1.0.29 was discovered to contain an abort in CWriter::Write.",
"id": "GHSA-835w-28hj-65xx",
"modified": "2022-11-01T19:00:29Z",
"published": "2022-10-29T12:00:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-43283"
},
{
"type": "WEB",
"url": "https://github.com/WebAssembly/wabt/issues/1985"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-83GQ-52Q2-4F4V
Vulnerability from github – Published: 2024-06-09 15:31 – Updated: 2024-06-09 15:31IBM Engineering Lifecycle Optimization Publishing 7.0.2 and 7.03 could allow a remote attacker to upload arbitrary files, caused by the improper validation of file extensions. By sending a specially crafted request, a remote attacker could exploit this vulnerability to upload a malicious file, which could allow the attacker to execute arbitrary code on the vulnerable system. IBM X-Force ID: 268751.
{
"affected": [],
"aliases": [
"CVE-2023-45188"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-09T13:15:49Z",
"severity": "MODERATE"
},
"details": "IBM Engineering Lifecycle Optimization Publishing 7.0.2 and 7.03 could allow a remote attacker to upload arbitrary files, caused by the improper validation of file extensions. By sending a specially crafted request, a remote attacker could exploit this vulnerability to upload a malicious file, which could allow the attacker to execute arbitrary code on the vulnerable system. IBM X-Force ID: 268751.",
"id": "GHSA-83gq-52q2-4f4v",
"modified": "2024-06-09T15:31:09Z",
"published": "2024-06-09T15:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-45188"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/268751"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/pages/node/7156757"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-83JR-29H8-JH58
Vulnerability from github – Published: 2022-03-20 00:00 – Updated: 2022-03-29 00:01Classcms v2.5 and below contains an arbitrary file upload via the component \class\classupload. This vulnerability allows attackers to execute code injection via a crafted .txt file.
{
"affected": [],
"aliases": [
"CVE-2022-25581"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-03-18T23:15:00Z",
"severity": "HIGH"
},
"details": "Classcms v2.5 and below contains an arbitrary file upload via the component \\class\\classupload. This vulnerability allows attackers to execute code injection via a crafted .txt file.",
"id": "GHSA-83jr-29h8-jh58",
"modified": "2022-03-29T00:01:32Z",
"published": "2022-03-20T00:00:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-25581"
},
{
"type": "WEB",
"url": "https://github.com/k0xx11/Vulscve/blob/master/classcms2.5-rce.md"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-83MG-Q2HX-3HJ4
Vulnerability from github – Published: 2025-11-11 06:30 – Updated: 2025-11-11 06:30The WP移行専用プラグイン for CPI plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the Cpiwm_Import_Controller::import function in all versions up to, and including, 1.0.2. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.
{
"affected": [],
"aliases": [
"CVE-2025-11170"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-11T04:15:41Z",
"severity": "CRITICAL"
},
"details": "The WP\u79fb\u884c\u5c02\u7528\u30d7\u30e9\u30b0\u30a4\u30f3 for CPI plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the Cpiwm_Import_Controller::import function in all versions up to, and including, 1.0.2. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site\u0027s server which may make remote code execution possible.",
"id": "GHSA-83mg-q2hx-3hj4",
"modified": "2025-11-11T06:30:20Z",
"published": "2025-11-11T06:30:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-11170"
},
{
"type": "WEB",
"url": "https://wordpress.org/plugins/cpi-wp-migration"
},
{
"type": "WEB",
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/8a96d6d5-a5e3-4648-902b-f9d1f8e57e5c?source=cve"
}
],
"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-83P2-3VFV-J3JP
Vulnerability from github – Published: 2022-05-14 02:18 – Updated: 2022-05-14 02:18There is a PHP code upload vulnerability in WeaselCMS 0.3.6 via index.php because code can be embedded at the end of a .png file when the image/png content type is used.
{
"affected": [],
"aliases": [
"CVE-2018-16352"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-09-02T22:29:00Z",
"severity": "CRITICAL"
},
"details": "There is a PHP code upload vulnerability in WeaselCMS 0.3.6 via index.php because code can be embedded at the end of a .png file when the image/png content type is used.",
"id": "GHSA-83p2-3vfv-j3jp",
"modified": "2022-05-14T02:18:48Z",
"published": "2022-05-14T02:18:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-16352"
},
{
"type": "WEB",
"url": "https://github.com/alterebro/WeaselCMS/issues/8"
}
],
"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-83PM-XJC4-CG4W
Vulnerability from github – Published: 2022-03-27 00:00 – Updated: 2026-07-05 15:30The web management console of CheckMK Enterprise Edition (versions 1.5.0 to 2.0.0p9) does not properly sanitise the uploading of ".mkp" files, which are Extension Packages, making remote code execution possible. Successful exploitation requires access to the web management interface, either with valid credentials or with a hijacked session of a user with administrator role.
{
"affected": [],
"aliases": [
"CVE-2021-40905"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-03-25T23:15:00Z",
"severity": "HIGH"
},
"details": "The web management console of CheckMK Enterprise Edition (versions 1.5.0 to 2.0.0p9) does not properly sanitise the uploading of \".mkp\" files, which are Extension Packages, making remote code execution possible. Successful exploitation requires access to the web management interface, either with valid credentials or with a hijacked session of a user with administrator role.",
"id": "GHSA-83pm-xjc4-cg4w",
"modified": "2026-07-05T15:30:26Z",
"published": "2022-03-27T00:00:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-40905"
},
{
"type": "WEB",
"url": "https://docs.checkmk.com/latest/en/mkps.html"
},
{
"type": "WEB",
"url": "https://github.com/Edgarloyola/CVE-2021-40905"
},
{
"type": "WEB",
"url": "http://checkmk.com"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-83PX-QCVF-3RV7
Vulnerability from github – Published: 2022-05-14 01:28 – Updated: 2022-05-14 01:28An issue was discovered in OFCMS before 1.1.3. Remote attackers can execute arbitrary code because blocking of .jsp and .jspx files does not consider (for example) file.jsp::$DATA to the admin/comn/service/editUploadImage URI.
{
"affected": [],
"aliases": [
"CVE-2019-9609"
],
"database_specific": {
"cwe_ids": [
"CWE-434"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-03-06T22:29:00Z",
"severity": "HIGH"
},
"details": "An issue was discovered in OFCMS before 1.1.3. Remote attackers can execute arbitrary code because blocking of .jsp and .jspx files does not consider (for example) file.jsp::$DATA to the admin/comn/service/editUploadImage URI.",
"id": "GHSA-83px-qcvf-3rv7",
"modified": "2022-05-14T01:28:00Z",
"published": "2022-05-14T01:28:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-9609"
},
{
"type": "WEB",
"url": "https://www.seebug.org/vuldb/ssvid-97830"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/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.