Bug 2294868 (CVE-2024-34703)

Summary: CVE-2024-34703 botan: Denial of Service Due to Overly Large Elliptic Curve Parameters
Product: [Other] Security Response Reporter: Mauro Matteo Cascella <mcascell>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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Fixed In Version: botan 3.3.0, botan 2.19.4 Doc Type: ---
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A flaw was found in Botan. X.509 certificates can identify elliptic curves using either an object identifier or explicit encoding of the parameters. This flaw allows an attacker to present an ECDSA X.509 certificate using explicit encoding where the parameters are very large. The POC used a 16Kbit prime for this purpose. When parsing the parameter is checked to be prime, it causes excessive computation.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2294869, 2294870, 2295888, 2295889    
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Description Mauro Matteo Cascella 2024-07-01 06:13:02 UTC 
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.

References:
https://github.com/randombit/botan/commit/08c404b23740babee1f6aa51b54e966029aadee4
https://github.com/randombit/botan/commit/94e9154c143aa5264da6254a6a1be5bc66ee2b5a
https://github.com/randombit/botan/security/advisories/GHSA-w4g2-7m2h-7xj7
Comment 1 Mauro Matteo Cascella 2024-07-01 06:13:21 UTC 
Created botan2 tracking bugs for this issue:

Affects: epel-all [bug 2294869]
Affects: fedora-all [bug 2294870]