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# Secret Box
While reviewing the source code, we come across a query responsible for storing user secrets:
```
INSERT INTO secrets(owner_id, content) VALUES ('${userId}', '${content}')
```
At first glance, this looks normal, but the issue lies in how the `content` parameter is handled. The user input is directly embedded into the SQL query without any sanitization or parameterization. This opens the door for SQL Injection, as we can break out of the intended query structure and inject our own SQL.
Instead of submitting normal text in the secret field, we craft a payload designed to execute a subquery:
```
'|| (SELECT content FROM secrets LIMIT 1) ||'
```
Under normal conditions, the query would execute like this:
```
VALUES ('user_id', 'input')
```
However, after injecting our payload, the query transforms into:
```
VALUES ('user_id', ''|| (SELECT content FROM secrets LIMIT 1) ||'')
```
Here, the application concatenates the result of the subquery into the `content` field. Instead of storing our input, the database executes the injected SQL and fetches the first entry from the `secrets` table.
As a result, we successfully retrieve sensitive data from the database, which most likely belongs to an admin or another user. This confirms the presence of a SQL Injection vulnerability caused by unsafe handling of user input.
---
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