MELSEC iQ-F Series FX5U-32MT/ES: Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
CVE-2022-40267 is a critical-severity incorrect usage of seeds in pseudo-random number generator (PRNG) vulnerability in MELSEC iQ-F Series FX5U-32MT/ES from Mitsubishi Electric, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected MELSEC iQ-F Series FX5U-32MT/ES versions: serial number 17X**** or later, and versions 1.280 and prior. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.24% chance of exploitation within 30 days, higher than 70% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of MELSEC iQ-F Series FX5U-32MT/ES you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on mitsubishielectric.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 |
|---|---|---|---|
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-32MT/ES | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-64MT/ES | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Seres FX5U-80MT/ES | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-32MR/ES | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-64MR/ES | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-80MR/ES | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-32MT/DS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-64MT/DS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-80MT/DS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-32MR/DS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-64MR/DS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-80MR/DS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-32MT/ESS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-64MT/ESS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-80MT/ESS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-32MT/DSS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-64MT/DSS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5U-80MT/DSS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-32MT/D | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-64MT/D | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-96MT/D | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-32MT/DSS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-64MT/DSS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-96MT/DSS | serial number 17X**** or later, and versions 1.280 and prior | Not stated |
| Mitsubishi Electric | MELSEC iQ-F Series FX5UC-32MT/DS-TS | versions 1.280 and prior | Not stated |
Version data comes from the organisation that assigned the CVE; 35 further products are omitted here. 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
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.9 | Medium | CNA (yd.MitsubishiElectric.co.jp) |
| CVSS 3.1 | 9.1 | Critical | NVD |
Official description
Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-xMy/z (x=32,64,80, y=T,R, z=ES,DS,ESS,DSS) with serial number 17X**** or later, and versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-xMy/z (x=32,64,80, y=T,R, z=ES,DS,ESS,DSS) with serial number 179**** and prior, and versions 1.074 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-xMy/z (x=32,64,96, y=T, z=D,DSS)) with serial number 17X**** or later, and versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-xMy/z (x=32,64,96, y=T, z=D,DSS)) with serial number 179**** and prior, and versions 1.074 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DS-TS versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DSS-TS versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-xMy/z (x=24,40,60, y=T,R, z=ES,ESS) versions 1.042 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-xMy/ES-A (x=24,40,60, y=T,R) versions 1.043 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-xMy/z (x=30,40,60,80, y=T,R, z=ES,ESS) versions 1.003 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MR/DS-TS versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-R Series R00/01/02CPU versions 33 and prior, Mitsubishi Electric Corporation MELSEC iQ-R Series R04/08/16/32/120(EN)CPU versions 66 and prior allows a remote unauthenticated attacker to access the Web server function by guessing the random numbers used for authentication from several used random numbers.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)
The product uses a Pseudo-Random Number Generator (PRNG) but does not correctly manage seeds.
More Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG) vulnerabilities (CWE-335)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
- jvn.jp/vu/JVNVU99673580/index.htmlMitigation, Third Party Advisory
- cisa.gov/uscert/ics/advisories/icsa-23-017-02Mitigation, Third Party Advisory, US Government Resource
Other references
Other vulnerabilities in MELSEC iQ-F Series FX5U-32MT/ES
- 7.5 High severity
- 7.3 High severity
- 9.1 Critical severity
- 8.1 High severity
- 7.5 High severity
Recent Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG) vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
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