CyberSecBulletin
CVE-2024-34703NVD status: Deferred

botan: Asymmetric Resource Consumption (Amplification)

Published Updated By the CyberSecBulletin desk

CVE-2024-34703 is a high-severity asymmetric resource consumption (amplification) vulnerability in botan from Randombit, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 3.3.1, 2.19.4 as the first without the flaw, so updating botan to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.5% 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 botan to 3.3.1 or 2.19.4, whichever matches your release line, 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
Randombitbotan>= 3.0.0-alpha0, < 3.3.0; < 2.19.4; 3.30 up to, but not including, 3.3.1; before 2.19.43.3.1, 2.19.4

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
NoneNo data is disclosed.
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:N/I:N/A:H. Scored by CNA (github.com).

Official description

Botan is a C++ cryptography library. X.509 certificates can identify elliptic curves using either an object identifier or using explicit encoding of the parameters. Prior to versions 3.3.0 and 2.19.4, an attacker could present an ECDSA X.509 certificate using explicit encoding where the parameters are very large. The proof of concept used a 16Kbit prime for this purpose. When parsing, the parameter is checked to be prime, causing excessive computation. This was patched in 2.19.4 and 3.3.0 to allow the prime parameter of the elliptic curve to be at most 521 bits. No known workarounds are available. Note that support for explicit encoding of elliptic curve parameters is deprecated in Botan.

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

The underlying weakness: Asymmetric Resource Consumption (Amplification)

The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is asymmetric.

How developers prevent this class of flaw

  • An application must make resources available to a client commensurate with the client's access level.
  • An application must, at all times, keep track of allocated resources and meter their usage appropriately.
  • Consider disabling resource-intensive algorithms on the server side, such as Diffie-Hellman key exchange.

More Asymmetric Resource Consumption (Amplification) vulnerabilities (CWE-405)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in botan

All botan vulnerabilities

Recent Asymmetric Resource Consumption (Amplification) vulnerabilities

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