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Bug 1758587 - OpenSSL will send unexpected alert for too short ciphertext with specific ciphersuites [rhel-8]
Summary: OpenSSL will send unexpected alert for too short ciphertext with specific cip...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: openssl
Version: 8.0
Hardware: Unspecified
OS: Unspecified
low
low
Target Milestone: rc
: 8.0
Assignee: Tomas Mraz
QA Contact: Hubert Kario
URL:
Whiteboard:
Depends On:
Blocks: 1758602
TreeView+ depends on / blocked
 
Reported: 2019-10-04 14:42 UTC by Hubert Kario
Modified: 2020-05-29 00:57 UTC (History)
0 users

Fixed In Version: openssl-1.1.1c-9.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 1758602 (view as bug list)
Environment:
Last Closed: 2020-04-28 16:52:04 UTC
Type: Bug
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github openssl openssl pull 10093 0 'None' closed Send bad_record_mac instead of decryption_failed 2020-12-15 09:24:22 UTC
Github tomato42 tlsfuzzer pull 597 0 'None' closed More CBC tests 2020-12-15 09:24:22 UTC
Red Hat Product Errata RHSA-2020:1840 0 None None None 2020-04-28 16:52:50 UTC

Description Hubert Kario 2019-10-04 14:42:37 UTC
Description of problem:
When the ciphertext is too small to contain IV, MAC and padding, openssl will send decryption_failed alert instead of the bad_record_mac.
This happens only for ciphers that do not use the "stiched" implementation of a cipher that combines the symmetric cipher with the HMAC.

Version-Release number of selected component (if applicable):
openssl-1.1.1c-2.el8

How reproducible:
always

Steps to Reproduce:
1. send a 16 bytes long ciphertext in a TLS record after negotiating TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 or TLS_RSA_WITH_3DES_EDE_CBC_SHA

Actual results:
server replies with decryption_failed

Expected results:
bad_record_mac alert

Additional info:
since the check is based on publicly visible data (the length of ciphertext), the difference in alert returned can't be used as a padding oracle for decryption

Comment 1 Tomas Mraz 2019-10-04 15:05:00 UTC
Trivial fix.

Comment 11 errata-xmlrpc 2020-04-28 16:52:04 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2020:1840

Comment 12 Fedora Update System 2020-05-29 00:57:11 UTC
FEDORA-EPEL-2020-ff94ccbdec has been pushed to the Fedora EPEL 7 stable repository.
If problem still persists, please make note of it in this bug report.


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