Headline
GHSA-342q-2mc2-5gmp: @jmondi/url-to-png enables capture screenshot of localhost web services (unauthenticated pages)
Summary
The maintainer been contemplating whether FTP or other protocols could serve as useful functionalities, but there may not be a practical reason for it since we are utilizing headless Chrome to capture screenshots. The argument is based on the assumption that this package can function as a service.
The package includes an ALLOW_LIST
where the host can specify which services the user is permitted to capture screenshots of. By default, capturing screenshots of web services running on localhost, 127.0.0.1, or the [::] is allowed.
The maintainer is of the opinion that the package should also have a blacklist due to a potential vulnerability (or rather design oversight). If someone hosts this on a server, users could then capture screenshots of other web services running locally.
Unless this is strictly for web pages. Something similar here: https://github.com/follow-redirects/follow-redirects/issues/235 (localhost is intended for end users or hosts to deny, and the package is for HTTP/HTTPS.)
This is marked as a LOW
since the maintainer is not sure if this is a vulnerability, but it’s still best to highlight it. :)
PoC
Have a service like so running locally:
const http = require("http")
const server = http.createServer((req, res) => {
console.log("Received headers:", req.headers)
res.writeHead(200, { "Content-Type": "text/plain" })
res.end("Something private! But Hello from Server 2 :)")
})
server.listen(3001, () => {
console.log("Server two running on http://localhost:3001")
})
Run the package in dev mode, pnpm dev
. Feed these URLs:
http://localhost:3089/?url=http://[::]:3001&width=4000
http://localhost:3089/?url=http://localhost:3001&width=4000
http://localhost:3089/?url=http://127.0.01:3001&width=4000
<img width="622" alt="image" src="https://github.com/jasonraimondi/url-to-png/assets/42532003/21f1c883-ba00-4a15-83b8-922484fa4c2b">
Impact
Disclose internal web services?
Summary
The maintainer been contemplating whether FTP or other protocols could serve as useful functionalities, but there may not be a practical reason for it since we are utilizing headless Chrome to capture screenshots. The argument is based on the assumption that this package can function as a service.
The package includes an ALLOW_LIST where the host can specify which services the user is permitted to capture screenshots of. By default, capturing screenshots of web services running on localhost, 127.0.0.1, or the [::] is allowed.
The maintainer is of the opinion that the package should also have a blacklist due to a potential vulnerability (or rather design oversight). If someone hosts this on a server, users could then capture screenshots of other web services running locally.
Unless this is strictly for web pages. Something similar here: follow-redirects/follow-redirects#235 (localhost is intended for end users or hosts to deny, and the package is for HTTP/HTTPS.)
This is marked as a LOW since the maintainer is not sure if this is a vulnerability, but it’s still best to highlight it. :)
PoC
Have a service like so running locally:
const http = require(“http”)
const server = http.createServer((req, res) => { console.log("Received headers:", req.headers) res.writeHead(200, { "Content-Type": “text/plain” }) res.end("Something private! But Hello from Server 2 :)") })
server.listen(3001, () => { console.log(“Server two running on http://localhost:3001”) })
Run the package in dev mode, pnpm dev. Feed these URLs:
http://localhost:3089/?url=http://[::]:3001&width=4000
http://localhost:3089/?url=http://localhost:3001&width=4000
http://localhost:3089/?url=http://127.0.01:3001&width=4000
Impact
Disclose internal web services?
References
- GHSA-342q-2mc2-5gmp
- jasonraimondi/url-to-png@f62ff40