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Invalid root may become trusted root in The Update Framework (TUF)

High severity GitHub Reviewed Published Sep 9, 2020 in theupdateframework/python-tuf • Updated Feb 1, 2023

Package

pip tuf (pip)

Affected versions

< 0.12

Patched versions

0.12

Description

Impact

The Python TUF reference implementation tuf<0.12 will incorrectly trust a previously downloaded root metadata file which failed verification at download time. This allows an attacker who is able to serve multiple new versions of root metadata (i.e. by a man-in-the-middle attack) culminating in a version which has not been correctly signed to control the trust chain for future updates.

While investigating the reported vulnerability, we discovered that the detailed client workflow was not fully implemented. Specifically, for step 1.3 the newly downloaded root metadata was not being verified with a threshold of keys specified in the new root metadata file.
This missing step of the client workflow has been implemented in PR #1101, which is included in v0.14.0 of tuf.

Patches

A fix, is available in version 0.12 and newer.

Workarounds

No workarounds are known for this issue.

References

  • Pull request resolving the invalid root becoming trusted issue PR 885
  • Pull request implementing self verification of newly downloaded root metadata PR 1101

References

@joshuagl joshuagl published to theupdateframework/python-tuf Sep 9, 2020
Reviewed Sep 9, 2020
Published to the GitHub Advisory Database Sep 9, 2020
Published by the National Vulnerability Database Sep 9, 2020
Last updated Feb 1, 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

0.111%
(46th percentile)

Weaknesses

CVE ID

CVE-2020-15163

GHSA ID

GHSA-f8mr-jv2c-v8mg

Source code

Credits

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