How To Patch and Protect OpenSSL Vulnerability # CVE-2015-0291 CVE-2015-0204

A serious security problem has been found and patched in the OpenSSL Library. Multiple vulnerabilities have been discovered in OpenSSL on 19/March/2015. The Common Vulnerabilities and exposures project identifies the following issues:

1. OpenSSL 1.0.2 ClientHello sigalgs DoS (CVE-2015-0291) - Severity: High
2. Reclassified: RSA silently downgrades to EXPORT_RSA [Client] (CVE-2015-0204) - Severity: High
3. Multiblock corrupted pointer (CVE-2015-0290) - Severity: Moderate
4. Segmentation fault in DTLSv1_listen (CVE-2015-0207) - Severity: Moderate
5. Segmentation fault in ASN1_TYPE_cmp (CVE-2015-0286) - Severity: Moderate
6. Segmentation fault for invalid PSS parameters (CVE-2015-0208) - Severity: Moderate
7. ASN.1 structure reuse memory corruption (CVE-2015-0287) - Severity: Moderate
8. PKCS7 NULL pointer dereferences (CVE-2015-0289) - Severity: Moderate
9. Base64 decode (CVE-2015-0292) - Severity: Moderate
10. DoS via reachable assert in SSLv2 servers (CVE-2015-0293) - Severity: Moderate
11. Empty CKE with client auth and DHE (CVE-2015-1787) - Severity: Moderate
12. Handshake with unseeded PRNG (CVE-2015-0285) - Severity: Low
13. Use After Free following d2i_ECPrivatekey error (CVE-2015-0209) Severity: Low
14. X509_to_X509_REQ NULL pointer deref (CVE-2015-0288) Severity: Low

How bad will this actually be?

It is not bad as the heartbleed openssl bug disclosed in April 2014 in the OpenSSL cryptography library. But, new bug can cause "Denial of Service" and crash your services. It is good security practice, to quickly apply the patched version on your system and restart the affected services.

How to find openssl version on a Linux?

The syntax is as follows:

Find openssl version on a CentOS/RHEL/SL/Fedora Linux

openssl version
## or ##
sudo yum list installed openssl
 

Sample outputs:

Fig.01: How to RHEL/CentOS/Fedora Linux Find OpenSSL Version Command

A list of affected Linux distros

I recommend that you upgrade your openssl packages ASAP to avoid any security issues on both client and server systems powered by Linux based distro.

• RHEL version 6.x
• RHEL version 7.x
• CentoS Linux version 6.x
• CentoS Linux version 7.x
• Debian Linux stable (wheezy) 7.x
• Ubuntu Linux 14.10
• Ubuntu Linux 14.04 LTS
• Ubuntu Linux 12.04 LTS
• Ubuntu Linux 10.04 LTS

How to patch on a Linux?

Type the following commands as per your distro version/type:

## how do I find out my distro version? ##
lsb_release -a
## or use ## 
cat /etc/*-release

Sample outputs:

Gif 01: HowTo: Find Out My Linux Distribution Name and Version

CentOS/RHEL/Fedora Linux

Type the following yum command to patch openssl as root user to patch openssl:

sudo yum clean all

To install the updates, use the yum command as follows:

sudo yum update

To only update the OpenSSL package and its dependencies, use the following yum command:

sudo yum update openssl

Debian/Ubuntu Linux

Type the following apt-get commands to patch openssl as root user to patch openssl:

sudo apt-get update
sudo apt-get upgrade

Sample outputs:

Fig.04: OpenSSL patched on a Ubuntu Linux

Do I need to reboot my server/laptop/computer powered by Linux?

Short answer - yes, you need to reboot your computer/server to make all the necessary changes. Sysadmin should plan on updating as soon as possible or use maintenance reboot window:

sudo reboot

Long answer - It depends. You can avoid reboot by restarting required services. Fist, find all services that depend on the OpenSSL libraries, and restart them one-by-one using the service command:

### Debian/Ubuntu find out if service needed reboot ##
checkrestart -v
 
## Generic method ##
lsof | grep libssl | awk '{print $1}' | sort | uniq
 

Sample outputs:

hhvm
mysqld
nginx
php5-fpm

Restart the above services one-by-one, run:

sudo service restart hhvm restart
sudo service restart mysqld restart
sudo service restart nginx restart
sudo service restart php5-fpm restart