pyinstaller: Incorrect Permission Assignment for Critical Resource
CVE-2023-49797 is a high-severity incorrect permission assignment for critical resource vulnerability in pyinstaller, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected pyinstaller versions: < 5.13.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.32% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of pyinstaller you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Pyinstaller | pyinstaller | < 5.13.1 | Not stated |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA (github.com) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
PyInstaller bundles a Python application and all its dependencies into a single package. A PyInstaller built application, elevated as a privileged process, may be tricked by an unprivileged attacker into deleting files the unprivileged user does not otherwise have access to. A user is affected if **all** the following are satisfied: 1. The user runs an application containing either `matplotlib` or `win32com`. 2. The application is ran as administrator (or at least a user with higher privileges than the attacker). 3. The user's temporary directory is not locked to that specific user (most likely due to `TMP`/`TEMP` environment variables pointing to an unprotected, arbitrary, non default location). Either: A. The attacker is able to very carefully time the replacement of a temporary file with a symlink. This switch must occur exactly between `shutil.rmtree()`'s builtin symlink check and the deletion itself B: The application was built with Python 3.7.x or earlier which has no protection against Directory Junctions links. The vulnerability has been addressed in PR #7827 which corresponds to `pyinstaller >= 5.13.1`. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Permission Assignment for Critical Resource
The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.
How developers prevent this class of flaw
- When using a critical resource such as a configuration file, check to see if the resource has insecure permissions (such as being modifiable by any regular user), and generate an error or even exit the software if there is a possibility that the resource could have been modified by an unauthorized party.
- Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully defining distinct user groups, privileges, and/or roles. Map these against data, functionality, and the related resources. Then set the permissions accordingly. This will allow you to maintain more fine-grained control over your resources.
- During program startup, explicitly set the default permissions or umask to the most restrictive setting possible. Also set the appropriate permissions during program installation. This will prevent you from inheriting insecure permissions from any user who installs or runs the program.
More Incorrect Permission Assignment for Critical Resource vulnerabilities (CWE-732)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/pyinstaller/pyinstaller/pull/7827Issue Tracking
Other references
Other vulnerabilities in pyinstaller
- 7.0 High severity
Recent Incorrect Permission Assignment for Critical Resource vulnerabilities
- 9.1 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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