SR OS (7250 IXR, 7450 ESS, 7750 SR, 7950 IXR…: Incorrect Permission Assignment for Critical Resource
CVE-2023-6729 is a high-severity incorrect permission assignment for critical resource vulnerability in SR OS (7250 IXR, 7450 ESS, 7750 SR, 7950 IXR, VSR), 7705 SAR OS, 7210 SAS OS from Nokia, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, but only if a user takes part, for example by opening a link or file. Affected SR OS (7250 IXR, 7450 ESS, 7750 SR, 7950 IXR, VSR), 7705 SAR OS, 7210 SAS OS versions: All supported releases prior to Release 24. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.15% 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 service_router_operating_system to 24 or a later version.
- Read the advisory on nokia.com for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| Nokia | SR OS (7250 IXR, 7450 ESS, 7750 SR, 7950 IXR, VSR), 7705 SAR OS, 7210 SAS OS | All supported releases prior to Release 24 | Not stated |
| Nokia | service_router_operating_system | before 24 | 24 |
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
- RequiredA user must take an action such as opening a file or link.
- 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:R/S:U/C:H/I:H/A:H. Scored by CISA (ADP).
Official description
Nokia SR OS routers allow read-write access to the entire file system via SFTP or SCP for users configured with "access console." Consequently, a low privilege authenticated user with "access console" can read or replace the router configuration file as well as other files stored in the Compact Flash or SD card without using CLI commands. This type of attack can lead to a compromise or denial of service of the router after the system is rebooted.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Recent Incorrect Permission Assignment for Critical Resource vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
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