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Symlink following allows leaking out-of-bound manifests and JSON files from Argo CD repo-server

Moderate
jannfis published GHSA-6gcg-hp2x-q54h May 18, 2022

Package

gomod github.com/argoproj/argo-cd (Go)

Affected versions

0.7.0 through 2.1.14, 2.2.8, 2.3.3

Patched versions

2.3.4, 2.2.9, 2.1.15

Description

Impact

All unpatched versions of Argo CD starting with v0.7.0 are vulnerable to a symlink following bug allowing a malicious user with repository write access to leak sensitive files from Argo CD's repo-server.

A malicious Argo CD user with write access for a repository which is (or may be) used in a directory-type Application may commit a symlink which points to an out-of-bounds file.

  • If the target file is a valid JSON or YAML manifest file, and the resource is allowed in the Application, the attacker can read the contents of that manifest file. (In versions <2.3.2, <2.2.8, and <2.1.14, the attacker may read the files contents even if the resource is not allowed in the Application).
  • If the target file is valid JSON but is not a manifest file, the attacker may read the contents of the file.
  • If the target file is not valid JSON or YAML, the attacker may read partial file contents (usually just the first character of the file).

Sensitive files which could be leaked include manifest files from other Applications' source repositories (potentially decrypted files, if you are using a decryption plugin) or any JSON-formatted secrets which have been mounted as files on the repo-server.

Patches

A patch for this vulnerability has been released in the following Argo CD versions:

  • v2.3.4
  • v2.2.9
  • v2.1.15

Workarounds

  • If you are using >=v2.3.0 and do not have any Jsonnet/directory-type Applications, disable the Jsonnet/directory config management tool. The config key is called jsonnet.enable since the same build tool is used for both Jsonnet and plain-manifest ("directory") sources.

Mitigations

  • Avoid mounting JSON-formatted secrets as files on the repo-server.
  • Upgrade to >=2.3.0 to significantly reduce the risk of leaking out-of-bounds manifest files. Starting with 2.3.0, repository paths are randomized, and read permissions are restricted when manifests are not being actively being generated. This makes it very difficult to craft and use a malicious symlink.
  • Upgrade to >=2.3.3, >=2.2.8, or >= 2.1.14 to significantly reduce the risk of leaking the contents of (but not the existence of) out-of-bounds manifest files. These versions prevent attackers from loading manifests which are not permitted in the Project which governs the Application.

Best practices which can mitigate risk

  • Limit who has push access to manifest repositories.
  • Limit who is allowed to configure new source repositories.
  • Limit resource kinds and destinations allowed for Projects, and restrict user access to only the necessary Projects.

Credits

This vulnerability was originally discovered as part of the Trail of Bits audit, published March 12, 2021. The behavior was left unchanged at the time.

The vulnerability was independently re-discovered by @crenshaw-dev, who contributed the patch. A security audit by Ada Logics independently followed up on the Trail of Bits report around the same time.

References

For more information

Open an issue in the Argo CD issue tracker or discussions
Join us on Slack in channel #argo-cd

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVE ID

CVE-2022-24904

Weaknesses

Credits