Ubuntu 4.10 / 5.04 : openssl weak default configuration (USN-179-1)

medium Nessus Plugin ID 20589
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The remote Ubuntu host is missing one or more security-related patches.


The current default algorithm for creating 'message digests' (electronic signatures) for certificates created by openssl is MD5.
However, this algorithm is not deemed secure any more, and some practical attacks have been demonstrated which could allow an attacker to forge certificates with a valid certification authority signature even if he does not know the secret CA signing key.

Therefore all Ubuntu versions of openssl have now been changed to use SHA-1 by default. This is a more appropriate default algorithm for the majority of use cases; however, if you still want to use MD5 as default, you can revert this change by changing the two instances of 'default_md = sha1' to 'default_md = md5' in /etc/ssl/openssl.cnf.

A detailed explanation and further links can be found at


Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.


Update the affected libssl-dev, libssl0.9.7 and / or openssl packages.

Plugin Details

Severity: Medium

ID: 20589

File Name: ubuntu_USN-179-1.nasl

Version: 1.20

Type: local

Agent: unix

Published: 1/15/2006

Updated: 1/19/2021

Dependencies: ssh_get_info.nasl

Risk Information


Risk Factor: Low

Score: 3.4


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: AV:N/AC:L/Au:N/C:N/I:P/A:N

Temporal Vector: E:U/RL:OF/RC:C

Vulnerability Information

CPE: p-cpe:/a:canonical:ubuntu_linux:libssl-dev, p-cpe:/a:canonical:ubuntu_linux:libssl0.9.7, p-cpe:/a:canonical:ubuntu_linux:openssl, cpe:/o:canonical:ubuntu_linux:4.10, cpe:/o:canonical:ubuntu_linux:5.04

Required KB Items: Host/cpu, Host/Ubuntu, Host/Ubuntu/release, Host/Debian/dpkg-l

Exploit Ease: No exploit is required

Patch Publication Date: 9/9/2005

Vulnerability Publication Date: 9/9/2005

Reference Information

CVE: CVE-2005-2946

USN: 179-1

CWE: 310