SB2017090403 - Red Hat update for OpenSSH

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Main Vulnerability Database SB2017090403

SB2017090403 - Red Hat update for OpenSSH

Published: September 4, 2017 Updated: March 20, 2023

Security Bulletin ID SB2017090403
Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Information disclosure

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 security vulnerability.


1) User enumeration via covert timing channel (CVE-ID: CVE-2016-6210)

The vulnerability allows a remote attacker to enumerate users on system.

The vulnerability exists in most systems where the Blowfish algorithm runs faster than SHA256/SHA512. A remote unauthenticated attacker can determine valid usernames by sending a specially crafted request with a large password (approximately 10,000 characters) to the target ssh daemon. On systems where a valid user's password has been hashed with SHA256/SHA512, the response time will be shorter for a non-existent username than for a valid username.

Successful exploitation of this vulnerability may result in disclosure or user logins.


Remediation

Install update from vendor's website.

References