Bug 1990591 (CVE-2021-3798)

Summary:	CVE-2021-3798 openCryptoki: Soft token does not check if an EC key is valid
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	dan, jjelen, plautrba, than
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in openCryptoki. The openCryptoki Soft token does not check if an EC key is valid when an EC key is created via C_CreateObject, nor when C_DeriveKey is used with ECDH public data. This may allow a malicious user to extract the private key by performing an invalid curve attack.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-28 10:48:15 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1959894, 1959936, 1979173, 1990592, 1998233, 1998234
Bug Blocks:	1990593

Description Guilherme de Almeida Suckevicz 2021-08-05 16:55:52 UTC

It was discovered that openCryptoki incorrectly handled certain EC keys. An attacker could possibly use this issue to cause a invalid curve attack.

Reference:
https://packetstormsecurity.com/files/163741/USN-5031-1.txt

Upstream patch:
https://github.com/opencryptoki/opencryptoki/commit/4e3b43c3d8844402c04a66b55c6c940f965109f0

Comment 1 Guilherme de Almeida Suckevicz 2021-08-05 16:56:05 UTC

Created openCryptoki tracking bugs for this issue:

Affects: fedora-all [bug 1990592]

Comment 5 Mauro Matteo Cascella 2021-09-10 15:31:55 UTC

As mentioned in the Ubuntu launchpad bug [1] EC support has been introduced in the Soft token with OCK 3.15.0, so this issue only affects openCryptoki versions >= 3.15.0 while earlier openCryptoki releases are not affected. In particular, EC support was introduced through commit [2].

[1] https://bugs.launchpad.net/ubuntu/+source/opencryptoki/+bug/1928780
[2] https://github.com/opencryptoki/opencryptoki/commit/a179fd01a265a98194d9c06ec5958da1dd2ecae3

Comment 7 Mauro Matteo Cascella 2021-09-13 10:19:59 UTC

In an invalid curve attack, the attacker is able to trick the vulnerable application into using curve points outside of the intended elliptic curve, making it possible to (potentially) extract the private key. A cryptographic library implementing Elliptic Curve Cryptography (ECC) needs to make sure that only valid curve points will be processed, while invalid points are detected and discarded accordingly. This is what openCryptoki's patch aims to do by adding the missing check in fill_ec_key_from_pubkey() and fill_ec_key_from_privkey().

Comment 9 Mauro Matteo Cascella 2021-09-13 13:33:50 UTC

This issue has been addressed in Red Hat Enterprise Linux 8 via RHBA-2021:3054:

https://access.redhat.com/errata/RHBA-2021:3054