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remote code execution via git repo provider

Critical severity GitHub Reviewed Published Aug 25, 2021 in jupyterhub/binderhub • Updated Sep 9, 2023

Package

pip binderhub (pip)

Affected versions

< 0.2.0

Patched versions

0.2.0

Description

Impact

A remote code execution vulnerability has been identified in BinderHub, where providing BinderHub with maliciously crafted input could execute code in the BinderHub context, with the potential to egress credentials of the BinderHub deployment, including JupyterHub API tokens, kubernetes service accounts, and docker registry credentials. This may provide the ability to manipulate images and other user created pods in the deployment, with the potential to escalate to the host depending on the underlying kubernetes configuration.

Patches

Patch below, or on GitHub

From 9f4043d9dddc1174920e687773f27b7933f48ab6 Mon Sep 17 00:00:00 2001
From: Riccardo Castellotti <rcastell@cern.ch>
Date: Thu, 19 Aug 2021 15:49:43 +0200
Subject: [PATCH] Explicitly separate git-ls-remote options from positional
 arguments

---
 binderhub/repoproviders.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/binderhub/repoproviders.py b/binderhub/repoproviders.py
index f33347b..5d4b87c 100755
--- a/binderhub/repoproviders.py
+++ b/binderhub/repoproviders.py
@@ -484,7 +484,7 @@ class GitRepoProvider(RepoProvider):
             self.sha1_validate(self.unresolved_ref)
         except ValueError:
             # The ref is a head/tag and we resolve it using `git ls-remote`
-            command = ["git", "ls-remote", self.repo, self.unresolved_ref]
+            command = ["git", "ls-remote", "--", self.repo, self.unresolved_ref]
             result = subprocess.run(command, universal_newlines=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
             if result.returncode:
                 raise RuntimeError("Unable to run git ls-remote to get the `resolved_ref`: {}".format(result.stderr))
-- 
2.25.1

Workarounds

Disable the git repo provider by specifying the BinderHub.repo_providers config, e.g.:

from binderhub.repoproviders import (GitHubRepoProvider,
                            GitLabRepoProvider, GistRepoProvider,
                            ZenodoProvider, FigshareProvider, HydroshareProvider,
                            DataverseProvider)

c.BinderHub.repo_providers =  {
            'gh': GitHubRepoProvider,
            'gist': GistRepoProvider,
            'gl': GitLabRepoProvider,
            'zenodo': ZenodoProvider,
            'figshare': FigshareProvider,
            'hydroshare': HydroshareProvider,
            'dataverse': DataverseProvider,
        }

References

Credit: Jose Carlos Luna Duran (CERN) and Riccardo Castellotti (CERN).

For more information

If you have any questions or comments about this advisory:

References

@minrk minrk published to jupyterhub/binderhub Aug 25, 2021
Reviewed Aug 25, 2021
Published by the National Vulnerability Database Aug 25, 2021
Published to the GitHub Advisory Database Aug 30, 2021
Last updated Sep 9, 2023

Severity

Critical
9.7
/ 10

CVSS base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

CVE ID

CVE-2021-39159

GHSA ID

GHSA-9jjr-qqfp-ppwx

Source code

Credits

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