SIMATIC S7-200 SMART CPU CR40: Use of Insufficiently Random Values
CVE-2024-35292 is a high-severity use of insufficiently random values vulnerability in SIMATIC S7-200 SMART CPU CR40 from Siemens, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected SIMATIC S7-200 SMART CPU CR40 versions: all versions. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.39% 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
- Check which version of SIMATIC S7-200 SMART CPU CR40 you run against the affected versions below, and install the vendor's latest release.
- 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 |
|---|---|---|---|
| Siemens | SIMATIC S7-200 SMART CPU CR40 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU CR60 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU SR20 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU SR30 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU SR40 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU SR60 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU ST20 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU ST30 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU ST40 | all versions | Not stated |
| Siemens | SIMATIC S7-200 SMART CPU ST60 | all versions | Not stated |
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
- LowSome restricted data can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H. Scored by CNA (siemens.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.8 | High | CNA (siemens.com) |
| CVSS 3.1 | 8.2 | High | CNA (siemens.com) |
Official description
A vulnerability has been identified in SIMATIC S7-200 SMART CPU CR40 (6ES7288-1CR40-0AA0) (All versions), SIMATIC S7-200 SMART CPU CR60 (6ES7288-1CR60-0AA0) (All versions), SIMATIC S7-200 SMART CPU SR20 (6ES7288-1SR20-0AA0) (All versions), SIMATIC S7-200 SMART CPU SR20 (6ES7288-1SR20-0AA1) (All versions), SIMATIC S7-200 SMART CPU SR30 (6ES7288-1SR30-0AA0) (All versions), SIMATIC S7-200 SMART CPU SR30 (6ES7288-1SR30-0AA1) (All versions), SIMATIC S7-200 SMART CPU SR40 (6ES7288-1SR40-0AA0) (All versions), SIMATIC S7-200 SMART CPU SR40 (6ES7288-1SR40-0AA1) (All versions), SIMATIC S7-200 SMART CPU SR60 (6ES7288-1SR60-0AA0) (All versions), SIMATIC S7-200 SMART CPU SR60 (6ES7288-1SR60-0AA1) (All versions), SIMATIC S7-200 SMART CPU ST20 (6ES7288-1ST20-0AA0) (All versions), SIMATIC S7-200 SMART CPU ST20 (6ES7288-1ST20-0AA1) (All versions), SIMATIC S7-200 SMART CPU ST30 (6ES7288-1ST30-0AA0) (All versions), SIMATIC S7-200 SMART CPU ST30 (6ES7288-1ST30-0AA1) (All versions), SIMATIC S7-200 SMART CPU ST40 (6ES7288-1ST40-0AA0) (All versions), SIMATIC S7-200 SMART CPU ST40 (6ES7288-1ST40-0AA1) (All versions), SIMATIC S7-200 SMART CPU ST60 (6ES7288-1ST60-0AA0) (All versions), SIMATIC S7-200 SMART CPU ST60 (6ES7288-1ST60-0AA1) (All versions). Affected devices are using a predictable IP ID sequence number. This leaves the system susceptible to a family of attacks which rely on the use of predictable IP ID sequence numbers as their base method of attack and eventually could allow an attacker to create a denial of service condition.
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: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in SIMATIC S7-200 SMART CPU CR40
- 7.5 High severity
Recent Use of Insufficiently Random Values vulnerabilities
- 8.1 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
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