Ubuntu Security Notice 3061-1 - Eddie Harari discovered that OpenSSH incorrectly handled password hashing when authenticating non-existing users. A remote attacker could perform a timing attack and enumerate valid users. Tomas Kuthan, Andres Rojas, and Javier Nieto discovered that OpenSSH did not limit password lengths. A remote attacker could use this issue to cause OpenSSH to consume resources, leading to a denial of service. Various other issues were also addressed.
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Ubuntu Security Notice USN-3061-1
August 15, 2016
openssh vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS
- Ubuntu 12.04 LTS
Summary:
Several security issues were fixed in OpenSSH.
Software Description:
- openssh: secure shell (SSH) for secure access to remote machines
Details:
Eddie Harari discovered that OpenSSH incorrectly handled password hashing
when authenticating non-existing users. A remote attacker could perform a
timing attack and enumerate valid users. (CVE-2016-6210)
Tomas Kuthan, Andres Rojas, and Javier Nieto discovered that OpenSSH did
not limit password lengths. A remote attacker could use this issue to cause
OpenSSH to consume resources, leading to a denial of service.
(CVE-2016-6515)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 16.04 LTS:
openssh-server 1:7.2p2-4ubuntu2.1
Ubuntu 14.04 LTS:
openssh-server 1:6.6p1-2ubuntu2.8
Ubuntu 12.04 LTS:
openssh-server 1:5.9p1-5ubuntu1.10
In general, a standard system update will make all the necessary changes.
References:
http://www.ubuntu.com/usn/usn-3061-1
CVE-2016-6210, CVE-2016-6515
Package Information:
https://launchpad.net/ubuntu/+source/openssh/1:7.2p2-4ubuntu2.1
https://launchpad.net/ubuntu/+source/openssh/1:6.6p1-2ubuntu2.8
https://launchpad.net/ubuntu/+source/openssh/1:5.9p1-5ubuntu1.10