CyberSecBulletin
CVE-2023-34758NVD status: Modified

Sliver: Use of a Broken or Risky Cryptographic Algorithm

Published Updated By the CyberSecBulletin desk

CVE-2023-34758 is a high-severity use of a broken or risky cryptographic algorithm vulnerability in Sliver from BishopFox, with a CVSS 3.1 base score of 8.1 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 1.5.40 as the first without the flaw, so updating Sliver to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.59% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Sliver to 1.5.40 or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
BishopfoxSliver1.5.0 up to, but not including, 1.5.401.5.40

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
HighSuccess depends on conditions outside the attacker's control.
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:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

Sliver from v1.5.x to v1.5.39 has an improper cryptographic implementation, which allows attackers to execute a man-in-the-middle attack via intercepted and crafted responses.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use of a Broken or Risky Cryptographic Algorithm

The product uses a broken or risky cryptographic algorithm or protocol.

How developers prevent this class of flaw

  • Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms. With hardware, design the product at the Intellectual Property (IP) level so that one cryptographic algorithm can be replaced with another in the next generation of the hardware product.
  • Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Industry-standard implementations will save development time and may be more likely to avoid errors that can occur during implementation of cryptographic algorithms. Consider the ESAPI Encryption feature.

More Use of a Broken or Risky Cryptographic Algorithm vulnerabilities (CWE-327)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Advisories

Patches and release notes

Third-party and government advisories

Other vulnerabilities in Sliver

All Sliver vulnerabilities

Recent Use of a Broken or Risky Cryptographic Algorithm vulnerabilities

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