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Bug 1758602 - OpenSSL will send unexpected alert for too short ciphertext with specific ciphersuites [rhel-7]
Summary: OpenSSL will send unexpected alert for too short ciphertext with specific cip...
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: openssl
Version: 7.8
Hardware: Unspecified
OS: Unspecified
low
low
Target Milestone: rc
: ---
Assignee: Tomas Mraz
QA Contact: BaseOS QE Security Team
URL:
Whiteboard:
Depends On: 1758587
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-10-04 15:24 UTC by Alicja Kario
Modified: 2020-04-24 14:26 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of: 1758587
Environment:
Last Closed: 2019-10-07 06:15:59 UTC
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 2020-12-17 13:07:47 UTC
Github tomato42 tlsfuzzer pull 597 0 None closed More CBC tests 2020-12-17 13:07:45 UTC

Description Alicja Kario 2019-10-04 15:24:09 UTC 
+++ This bug was initially created as a clone of Bug #1758587 +++

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

--- Additional comment from Tomas Mraz on 2019-10-04 15:05:00 UTC ---

Trivial fix.
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