offensive-jwt

Name: offensive-jwt
Author: SnailSploit

43installs447forks

How to install offensive-jwt?

snailsploit/claude-red/offensive-jwt

$npx -y skills add SnailSploit/Claude-Red --skill offensive-jwt

Installs into the current project.

Summary

JWT attack methodology for penetration testers. Covers algorithm confusion (alg:none, RS256→HS256), weak HMAC secret brute force, kid parameter injection (SQLi, path traversal), jku/x5u/jwk header injection, JWKS cache poisoning, JWS/JWE confusion, timing attacks, and mobile JWT

Files · 1

View on GitHub

SKILL.md

1	## Overview
2
3	Comprehensive JWT attack checklist for offensive security engagements. Follow steps in order; apply each technique to the current target context and track which items have been completed.
4
5	## Quick Reference: Misconfigurations to Check
6
7	- Algorithm set to `none` — signature verification bypassed entirely
8	- Algorithm switching between `RSA` and `HMAC` (confusion attack)
9	- Weak or guessable HMAC secret (brute-forceable)
10	- `kid`, `jku`, `jwk`, `x5u` header parameters accepted without validation
11	- Expired or tampered tokens accepted by server
12	- Sensitive data stored unencrypted in payload
13
14	Useful tool: [JWT Tool](https://github.com/ticarpi/jwt_tool)
15
16	## Mechanisms
17
18	JWTs (RFC 7519) consist of three Base64URL-encoded parts: `header.payload.signature`.
19
20	Signing algorithms:
21
22	\| Algorithm \| Type \| Notes \|
23	\|-----------\|------\|-------\|
24	\| HS256/384/512 \| Symmetric HMAC \| Shared secret; confusion target \|
25	\| RS256/384/512 \| Asymmetric RSA \| Public key can be misused as HMAC secret \|
26	\| ES256/384/512 \| Asymmetric ECDSA \| \|
27	\| PS256/384/512 \| RSASSA-PSS \| \|
28	\| EdDSA (Ed25519/Ed448) \| Asymmetric \| \|
29	\| none \| Unsigned \| Critically insecure \|
30
31	Additional pitfalls:
32	- JWS/JWE confusion: server accepts encrypted token (JWE) where signed (JWS) is expected, or fails open on unexpected `typ`/`cty`
33	- JWKS retrieval: SSRF via `jku`/`x5u`, insecure TLS, poisoned key caching, `kid` collisions
34	- Token binding (DPoP, mTLS): incorrectly implemented allows replay from other clients
35
36	## Hunt: Identifying JWT Usage
37
38	1. Check `Authorization: Bearer <token>` headers in all requests
39	2. Look for cookies containing JWT structures (`eyJ...`)
40	3. Examine browser local/session storage
41	4. Decode the token at jwt.io or via BurpSuite JWT extension — inspect claims and header parameters
42	5. Note any `kid`, `jku`, `jwk`, `x5u` fields in the header — these are attack surfaces
43
44	## Vulnerability Map
45
46	```
47	JWT Vulnerabilities
48	├── Algorithm Bypass
49	│ ├── alg:none attack
50	│ └── RS256→HS256 confusion (public key as HMAC secret)
51	├── Weak Secret Key → Brute force
52	├── kid Parameter Injection
53	│ ├── SQL injection via kid
54	│ └── Path traversal via kid
55	├── Header Injection
56	│ ├── jwk (inline fake key)
57	│ ├── jku/x5u (remote attacker-controlled JWKS)
58	│ └── JWKS cache poisoning
59	└── Missing / Broken Validation
60	├── No signature check
61	├── Expired tokens accepted
62	└── iss/aud/exp not validated
63	```
64
65	## Vulnerabilities
66
67	### Algorithm Vulnerabilities
68
69	- alg:none — Some libraries disable signature validation when `alg` is `none` or a case variant (`None`, `NONE`, `nOnE`)
70	- Algorithm Confusion (RS256→HS256) — Server uses RSA public key as HMAC secret when attacker switches `alg` to HS256; attacker re-signs token with the public key
71	- Key ID (`kid`) Manipulation — Exploiting `kid` to load wrong keys or inject file paths / SQL; enforce strict lookups
72
73	### Signature Vulnerabilities
74
75	- Weak HMAC Secrets — Brute-forceable with dictionary or hashcat
76	- Missing Signature Validation — Token accepted without any verification
77	- Broken Validation — Implementation errors in signature checking logic
78
79	### Implementation Issues
80
81	- Missing Claims Validation — `exp`, `nbf`, `aud`, `iss` not verified
82	- Insufficient Entropy — Predictable JWT IDs or tokens
83	- No Expiration — Tokens valid indefinitely
84	- Insecure Transport — Token sent over HTTP
85	- Debug Leakage — Detailed error messages expose implementation
86
87	### Header Injection Attacks
88
89	- JWK Injection — Supply a custom attacker-controlled public key via the `jwk` header
90	- JKU Manipulation — Point `jku` (JWK Set URL) to attacker-controlled JWKS endpoint
91	- x5u Misuse — Load untrusted X.509 key URL; exploit lax TLS validation or open redirects
92	- JWKS Cache Poisoning — Force caches to accept attacker keys via `kid` collisions or response header manipulation
93	- `crit` Header Abuse — Server ignores unknown critical parameters, enabling bypass
94
95	### Information Disclosure
96
97	- Sensitive data (PII, credentials, session details) stored unencrypted in payload
98	- Internal service/backend information leaked via claims
99
100	## Additional Attack Vectors
101
102	### Mobile App JWT Storage
103
104	Android:
105	- `SharedPreferences`: Check if world-readable; location `/data/data/<package>/shared_prefs/`
106	- Keystore extraction: root device or exploit app
107	- Backup extraction: `adb backup -f backup.ab <package>` (if `allowBackup=true`)
108	- Tools: Frida, objection, MobSF
109
110	iOS:
111	- Keychain: Check `kSecAttrAcces

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Type

offensive-jwt

43installs447forks

View on GitHub

How to install offensive-jwt?

snailsploit/claude-red/offensive-jwt

$npx -y skills add SnailSploit/Claude-Red --skill offensive-jwt

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	## Overview
2
3	Comprehensive JWT attack checklist for offensive security engagements. Follow steps in order; apply each technique to the current target context and track which items have been completed.
4
5	## Quick Reference: Misconfigurations to Check
6
7	- Algorithm set to `none` — signature verification bypassed entirely
8	- Algorithm switching between `RSA` and `HMAC` (confusion attack)
9	- Weak or guessable HMAC secret (brute-forceable)
10	- `kid`, `jku`, `jwk`, `x5u` header parameters accepted without validation
11	- Expired or tampered tokens accepted by server
12	- Sensitive data stored unencrypted in payload
13
14	Useful tool: [JWT Tool](https://github.com/ticarpi/jwt_tool)
15
16	## Mechanisms
17
18	JWTs (RFC 7519) consist of three Base64URL-encoded parts: `header.payload.signature`.
19
20	Signing algorithms:
21
22	\| Algorithm \| Type \| Notes \|
23	\|-----------\|------\|-------\|
24	\| HS256/384/512 \| Symmetric HMAC \| Shared secret; confusion target \|
25	\| RS256/384/512 \| Asymmetric RSA \| Public key can be misused as HMAC secret \|
26	\| ES256/384/512 \| Asymmetric ECDSA \| \|
27	\| PS256/384/512 \| RSASSA-PSS \| \|
28	\| EdDSA (Ed25519/Ed448) \| Asymmetric \| \|
29	\| none \| Unsigned \| Critically insecure \|
30
31	Additional pitfalls:
32	- JWS/JWE confusion: server accepts encrypted token (JWE) where signed (JWS) is expected, or fails open on unexpected `typ`/`cty`
33	- JWKS retrieval: SSRF via `jku`/`x5u`, insecure TLS, poisoned key caching, `kid` collisions
34	- Token binding (DPoP, mTLS): incorrectly implemented allows replay from other clients
35
36	## Hunt: Identifying JWT Usage
37
38	1. Check `Authorization: Bearer <token>` headers in all requests
39	2. Look for cookies containing JWT structures (`eyJ...`)
40	3. Examine browser local/session storage
41	4. Decode the token at jwt.io or via BurpSuite JWT extension — inspect claims and header parameters
42	5. Note any `kid`, `jku`, `jwk`, `x5u` fields in the header — these are attack surfaces
43
44	## Vulnerability Map
45
46	```
47	JWT Vulnerabilities
48	├── Algorithm Bypass
49	│ ├── alg:none attack
50	│ └── RS256→HS256 confusion (public key as HMAC secret)
51	├── Weak Secret Key → Brute force
52	├── kid Parameter Injection
53	│ ├── SQL injection via kid
54	│ └── Path traversal via kid
55	├── Header Injection
56	│ ├── jwk (inline fake key)
57	│ ├── jku/x5u (remote attacker-controlled JWKS)
58	│ └── JWKS cache poisoning
59	└── Missing / Broken Validation
60	├── No signature check
61	├── Expired tokens accepted
62	└── iss/aud/exp not validated
63	```
64
65	## Vulnerabilities
66
67	### Algorithm Vulnerabilities
68
69	- alg:none — Some libraries disable signature validation when `alg` is `none` or a case variant (`None`, `NONE`, `nOnE`)
70	- Algorithm Confusion (RS256→HS256) — Server uses RSA public key as HMAC secret when attacker switches `alg` to HS256; attacker re-signs token with the public key
71	- Key ID (`kid`) Manipulation — Exploiting `kid` to load wrong keys or inject file paths / SQL; enforce strict lookups
72
73	### Signature Vulnerabilities
74
75	- Weak HMAC Secrets — Brute-forceable with dictionary or hashcat
76	- Missing Signature Validation — Token accepted without any verification
77	- Broken Validation — Implementation errors in signature checking logic
78
79	### Implementation Issues
80
81	- Missing Claims Validation — `exp`, `nbf`, `aud`, `iss` not verified
82	- Insufficient Entropy — Predictable JWT IDs or tokens
83	- No Expiration — Tokens valid indefinitely
84	- Insecure Transport — Token sent over HTTP
85	- Debug Leakage — Detailed error messages expose implementation
86
87	### Header Injection Attacks
88
89	- JWK Injection — Supply a custom attacker-controlled public key via the `jwk` header
90	- JKU Manipulation — Point `jku` (JWK Set URL) to attacker-controlled JWKS endpoint
91	- x5u Misuse — Load untrusted X.509 key URL; exploit lax TLS validation or open redirects
92	- JWKS Cache Poisoning — Force caches to accept attacker keys via `kid` collisions or response header manipulation
93	- `crit` Header Abuse — Server ignores unknown critical parameters, enabling bypass
94
95	### Information Disclosure
96
97	- Sensitive data (PII, credentials, session details) stored unencrypted in payload
98	- Internal service/backend information leaked via claims
99
100	## Additional Attack Vectors
101
102	### Mobile App JWT Storage
103
104	Android:
105	- `SharedPreferences`: Check if world-readable; location `/data/data/<package>/shared_prefs/`
106	- Keystore extraction: root device or exploit app
107	- Backup extraction: `adb backup -f backup.ab <package>` (if `allowBackup=true`)
108	- Tools: Frida, objection, MobSF
109
110	iOS:
111	- Keychain: Check `kSecAttrAcces

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