Bug 1885947 (CVE-2020-26570)

Summary:	CVE-2020-26570 opensc: heap-based buffer overflow in sc_oberthur_read_file
Product:	[Other] Security Response	Reporter:	Michael Kaplan <mkaplan>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	crypto-team, gmazyland, jjelen
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	opensc 0.21.0-rc1	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-05-18 20:36:33 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:	1885948, 1885949, 1887528
Bug Blocks:	1885958

Description Michael Kaplan 2020-10-07 10:51:32 UTC

The Oberthur smart card software driver in OpenSC before 0.21.0-rc1 has a heap-based buffer overflow in sc_oberthur_read_file.

References:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=24316
https://github.com/OpenSC/OpenSC/commit/6903aebfddc466d966c7b865fae34572bf3ed23e

Comment 1 Michael Kaplan 2020-10-07 10:52:19 UTC

Created opensc tracking bugs for this issue:

Affects: epel-6 [bug 1885949]
Affects: fedora-all [bug 1885948]

Comment 2 Todd Cullum 2020-10-08 19:35:29 UTC

Flaw summary:
sc_oberthur_read_file() in src/libopensc/pkcs15-oberthur.c attempts to read an invalid record from the card reader APDU interface by reading a record greater than file->record_count, causing an out-of-bounds write.

Comment 5 Todd Cullum 2020-10-12 18:25:48 UTC

Mitigation:

This flaw can be mitigated in cases where you can use opensc without the Oberthur driver enabled. In such cases, the vulnerable driver can be disabled by specifying them in /etc/opensc.conf card_drivers field in allowlist fashion.
One such example:

```
app default {
   card_drivers = cac, cac1, PIV-II;
}
```

This would only enable the cac, cac1, and PIV-II smart card drivers, and all others would be disabled, including the Oberthur driver. With the Oberthur driver disabled, this flaw is mitigated. It is important to list all drivers that you need in the card_drivers field so that they are not disabled too.

Comment 7 errata-xmlrpc 2021-05-18 13:35:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:1600 https://access.redhat.com/errata/RHSA-2021:1600

Comment 8 Product Security DevOps Team 2021-05-18 20:36:33 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-26570