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Remote code execution in dependabot-core branch names when cloning

High severity GitHub Reviewed Published Nov 13, 2020 in dependabot/dependabot-core • Updated Nov 6, 2023

Package

bundler dependabot-common (RubyGems)

Affected versions

>= 0.119.0.beta1, < 0.125.1

Patched versions

0.125.1
bundler dependabot-omnibus (RubyGems)
>= 0.119.0.beta1, < 0.125.1
0.125.1

Description

Impact

Remote code execution vulnerability in dependabot-common and dependabot-go_modules when a source branch name contains malicious injectable bash code.

For example, if Dependabot is configured to use the following source branch name: "/$({curl,127.0.0.1})", Dependabot will make a HTTP request to the following URL: 127.0.0.1 when cloning the source repository.

When Dependabot is configured to clone the source repository during an update, Dependabot runs a shell command to git clone the repository:

git clone --no-tags --no-recurse-submodules --depth=1 --branch=<BRANCH> --single-branch <GITHUB_REPO_URL> repo/contents/path

Dependabot will always clone the source repository for go_modules during the file fetching step and can be configured to clone the repository for other package managers using the FileFetcher class from dependabot-common.

source = Dependabot::Source.new(
  provider: "github",
  repo: "repo/name",
  directory: "/",
  branch: "/$({curl,127.0.0.1})",
)

repo_contents_path = "./file/path"
fetcher = Dependabot::FileFetchers.for_package_manager("bundler").
                  new(source: source, credentials: [],
                  repo_contents_path: repo_contents_path)
fetcher.clone_repo_contents

Patches

The fix was applied to version 0.125.1: dependabot/dependabot-core#2727

Workarounds

Escape the branch name prior to passing it to the Dependabot::Source class.

For example using shellwords:

require "shellwords"
branch = Shellwords.escape("/$({curl,127.0.0.1})")
source = Dependabot::Source.new(
  provider: "github",
  repo: "repo/name",
  directory: "/",
  branch: branch,
)

References

@feelepxyz feelepxyz published to dependabot/dependabot-core Nov 13, 2020
Reviewed Nov 13, 2020
Published to the GitHub Advisory Database Nov 13, 2020
Published by the National Vulnerability Database Nov 13, 2020
Last updated Nov 6, 2023

Severity

High

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
Required
Scope
Changed
Confidentiality
High
Integrity
High
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:R/S:C/C:H/I:H/A:N

EPSS score

1.368%
(87th percentile)

Weaknesses

CVE ID

CVE-2020-26222

GHSA ID

GHSA-23f7-99jx-m54r

Source code

Credits

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