Nostromo: Improper Limitation of a Pathname to a Restricted Directory
CVE-2022-48253 is a critical-severity improper limitation of a pathname to a restricted directory vulnerability in Nostromo from Nazgul, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2.1 as the first without the flaw, so updating Nostromo to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 3.65% chance of exploitation within 30 days, higher than 90% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Nostromo to 2.1 or a later version.
- Read the advisory on nazgul.ch 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.
Affected products and versions
Version data comes from NVD's product matching. 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
- 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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 3.1 | 9.8 | Critical | CISA (ADP) |
Official description
nhttpd in Nostromo before 2.1 is vulnerable to a path traversal that may allow an attacker to execute arbitrary commands on the remote server. The vulnerability occurs when the homedirs option is used.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- nazgul.ch/dev/nostromo_cl.txtRelease Notes
Technical write-ups (may include proof of concept)
- soteritsecurity.com/blog/2023/01/nostromo_from_directory_traversal_to_RCE.htmlExploit, Third Party Advisory
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 7.5 High severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.1 High severity
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