In early 2023, Cisco quietly patched a vulnerability—now tracked as CVE-2023-20039—in their Industrial Network Director (IND) software. This bug allowed any local, authenticated user to read sensitive application data, thanks to lax default file permissions. If you run Cisco IND and haven’t updated, or just want to understand what happened, this long-read breaks it all down:

At its core, CVE-2023-20039 is an information disclosure bug. Here’s the gist

- Cisco IND’s application data directory (where config files, logs, and sometimes secrets are stored) was left with overly permissive file permissions after installation.
- Any logged-in user on the underlying OS could open, copy, or read files in this directory, with no restrictions.

These files might include: passwords, configuration info, internal tokens, or API credentials.

Direct link to Cisco’s advisory:
> Cisco CVE-2023-20039 Security Advisory

Why is This Serious?

Even though attackers need to be local and authenticated (not remote outsiders), in enterprise or shared environments this still breaks security best practices.

- Privileged escalation: Sensitive files (such as database connection strings or API tokens) can help a user further elevate access.

IND installer sets permissions for its data directory.

2. Instead of restricting access (e.g., only the user running IND), it leaves them world-readable or user-group-readable.

A common problematic permission might look like this (using Linux notation)

drwxrwxrwx  2 root root   4096 Mar 22 08:14 application_data/

or for files inside

-rw-r--r--  1 induser indgroup   789 Mar 22 08:16 config.cfg

Ideally, config files containing secrets should be

-rw-------  1 induser indgroup   789 Mar 22 08:16 config.cfg

Exploit Example: How Attackers Could Read Sensitive Data

Prerequisite: You are already a local, authenticated user on the Cisco IND host.

Goal: Grab sensitive contents from the IND application data directory.

Let’s say application data is under /opt/cisco/ind/appdata/.

Step 1: List application data

ls -l /opt/cisco/ind/appdata/

Sample output (showing world-readable files)

-rw-r--r-- 1 induser indgroup 2048 Mar 22 08:15 IND_config.yaml
-rw-r--r-- 1 induser indgroup 1024 Mar 22 08:15 IND_secrets.json

Step 2: Dump the secrets file

cat /opt/cisco/ind/appdata/IND_secrets.json

Sample excerpt

{
  "db_password": "p@sswrd",
  "api_key": "12345-abcde-secret",
  "admin_user": "admin"
}

Step 3: Use those secrets (for example, try database access, API requests, etc.)

*(Not shown for legality, but you get the idea: you now have key internal info.)*

Fixes and Remediation

Cisco has released fixed versions of IND.
There are no easy workarounds since the permissions are set by the installer and affect app operation.

Update your Cisco IND software to a fixed release as soon as possible.

- Reference: Cisco download page

If you can’t patch immediately, you might attempt to re-apply strict permissions

chmod -R 700 /opt/cisco/ind/appdata/

But this does not guarantee there are no other issues or that your changes won’t get overwritten by updates. Only patching is fully supported.

More Resources

- Cisco Official Advisory for CVE-2023-20039
- NIST NVD CVE-2023-20039 Entry

Conclusion

CVE-2023-20039 is a useful reminder that even local file permission issues can become serious liabilities, especially in environments with multiple users or high compliance requirements. Patch your Cisco IND deployments now, and always audit file permissions after installing or updating key infrastructure apps.


*Thanks for reading! Stay safe out there, and keep your systems (and file permissions!) up to date.*

Timeline

Published on: 11/15/2024 15:20:49 UTC