MXsecurity Series: Use of Insufficiently Random Values
CVE-2023-39979 is a critical-severity use of insufficiently random values vulnerability in MXsecurity Series from Moxa, 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. Affected MXsecurity Series versions: 1.0 through 1.0.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.98% chance of exploitation within 30 days, higher than 63% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Mxsecurity to 1.1.0 or a later version.
- Read the advisory on moxa.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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Moxa | MXsecurity Series | 1.0 through 1.0.1 | Not stated |
| Moxa | Mxsecurity | before 1.1.0 | 1.1.0 |
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
- 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 | CNA (moxa.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
There is a vulnerability in MXsecurity versions prior to 1.0.1 that can be exploited to bypass authentication. A remote attacker might access the system if the web service authenticator has insufficient random values.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Insufficiently Random Values
The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.
How developers prevent this class of flaw
- Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds. In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts. Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a random enough number.
- Consider a PRNG that re-seeds itself as needed from high quality pseudo-random output sources, such as hardware devices.
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems. Consult FIPS 140-2 Annex C (Approved Random Number Generators).
More Use of Insufficiently Random Values vulnerabilities (CWE-330)
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
Other vulnerabilities in MXsecurity Series
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 9.8 Critical severity
- 8.8 High severity
Recent Use of Insufficiently Random Values vulnerabilities
- 9.1 Critical severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
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