monkeytype: Improper Control of Generation of Code
CVE-2024-41127 is a critical-severity improper control of generation of code vulnerability in monkeytype from Monkeytypegame, with a CVSS 3.1 base score of 9.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected monkeytype versions: < 24.30.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.88% chance of exploitation within 30 days, higher than 60% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update monkeytype to 24.30.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Monkeytypegame | monkeytype | < 24.30.0 | Not stated |
| Monkeytype | monkeytype | before 24.30.0 | 24.30.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.3 | High | CNA (github.com) |
| CVSS 3.1 | 9.6 | Critical | NVD |
Official description
Monkeytype is a minimalistic and customizable typing test. Monkeytype is vulnerable to Poisoned Pipeline Execution through Code Injection in its ci-failure-comment.yml GitHub Workflow, enabling attackers to gain pull-requests write access. The ci-failure-comment.yml workflow is triggered when the Monkey CI workflow completes. When it runs, it will download an artifact uploaded by the triggering workflow and assign the contents of ./pr_num/pr_num.txt artifact to the steps.pr_num_reader.outputs.content WorkFlow variable. It is not validated that the variable is actually a number and later it is interpolated into a JS script allowing an attacker to change the code to be executed. This issue leads to pull-requests write access. This vulnerability is fixed in 24.30.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Control of Generation of Code
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
How developers prevent this class of flaw
- Refactor your program so that you do not have to dynamically generate code.
- Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
More Improper Control of Generation of Code vulnerabilities (CWE-94)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Technical write-ups (may include proof of concept)
- securitylab.github.com/advisories/GHSL-2024-167_monkeytypeExploit, Third Party Advisory
Other vulnerabilities in monkeytype
- 9.3 Critical severity
- 7.5 High severity
Recent Improper Control of Generation of Code vulnerabilities
- 7.1 High severity
- 9.8 Critical severity
- 9.4 Critical severity
- 9.6 Critical severity
- 8.8 High severity
- 8.8 High severity
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