Junos OS Evolved: Incorrect Default Permissions
CVE-2023-28966 is a high-severity incorrect default permissions vulnerability in Junos OS Evolved from Juniper Networks, 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. The record lists versions 20.4R3-S5-EVO, 21.2R3-EVO, 21.3R2-EVO as the first without the flaw, so updating Junos OS Evolved to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.16% 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
- Update Junos OS Evolved to 20.4R3-S5-EVO or 21.2R3-EVO or 21.3R2-EVO, whichever matches your release line, or a later version.
- Read the advisory on supportportal.juniper.net for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Juniper Networks | Junos OS Evolved | before 20.4R3-S5-EVO; 21.2 up to, but not including, 21.2R3-EVO; 21.3 up to, but not including, 21.3R2-EVO | 20.4R3-S5-EVO, 21.2R3-EVO, 21.3R2-EVO |
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 CNA (juniper.net).
Official description
An Incorrect Default Permissions vulnerability in Juniper Networks Junos OS Evolved allows a low-privileged local attacker with shell access to modify existing files or execute commands as root. The issue is caused by improper file and directory permissions on certain system files, allowing an attacker with access to these files and folders to inject CLI commands as root. This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R3-S5-EVO; 21.2 versions prior to 21.2R3-EVO; 21.3 versions prior to 21.3R2-EVO.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Default Permissions
During installation, installed file permissions are set to allow anyone to modify those files.
How developers prevent this class of flaw
- The architecture needs to access and modification attributes for files to only those users who actually require those actions.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
More Incorrect Default Permissions vulnerabilities (CWE-276)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Junos OS Evolved
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
Recent Incorrect Default Permissions vulnerabilities
- 7.1 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
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