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Enterprise Linux 5.6 to 5.7 risk report

Mark J. Cox published on 2011-07-27T00:00:00+00:00, last updated 2016-06-20T19:01:36+00:00

Red Hat Enterprise Linux 5.7 was released last week (July 2011), six months since the release of 5.6 in January 2011. So let's use this opportunity to take a quick look back over the vulnerabilities and security updates made in that time, specifically for Red Hat Enterprise Linux 5 Server.

Errata count

The chart below illustrates the total number of security updates issued for Red Hat Enterprise Linux 5 Server if you had installed 5.6, up to and including the 5.7 release, broken down by severity. It's split into two columns, one for the packages you'd get if you did a default install, and the other if you installed every single package (which is unlikely as it would involve quite a bit of manual effort to select every one). For a given installation, the number of package updates and vulnerabilities that affected you will depend on exactly what packages you have installed or removed.

So, for a default install, from release of 5.6 up to and including 5.7, we shipped 27 advisories to address 109 vulnerabilities. 3 advisories were rated critical, 12 were important, and the remaining 12 were moderate and low.

Or, for all packages, from release of 5.6 to and including 5.7, we shipped 58 advisories to address 172 vulnerabilities. 4 advisories were rated critical, 20 were important, and the remaining 34 were moderate and low.

Critical vulnerabilities

The 4 critical advisories addressed 34 critical vulnerabilities across just 2 different packages:

  1. An update to OpenJDK 6 Java Runtime Environment, (June 2011) where a web site hosting a malicious Java applet could potentially run arbitrary code as the user.
  2. Three updates to Firefox (March 2011, April 2011, June 2011) where a malicious web site could potentially run arbitrary code as the user running Firefox.

Updates to correct all of the 34 critical vulnerabilities were available via Red Hat Network either the same day or the next calendar day after the issues were public.

Overall, for Red Hat Enterprise Linux 5 since release until 5.7, 97% of critical vulnerabilities have had an update available to address them available from the Red Hat Network either the same day or the next calendar day after the issue was public.

Other significant vulnerabilities

Although not in the definition of critical severity, also of interest during this period were a couple of flaws that were easily exploitable:

  • A flaw in dhcp, CVE-2011-0997, fixed by RHSA-2011:0428, where a malicious DHCP server could send a response that could lead to arbitrary code execution on connecting clients.
  • A flaw in glibc, CVE-2011-0536, fixed by RHSA-2011:0412, where a local user could gain root privileges.

In addition, updates to Firefox and NSS were made to blacklist a number of compromised SSL certificates.

Previous update releases

To compare these statistics with previous update releases we need to take into account that the time between each update release is different. So looking at a default installation and calculating the number of advisories per month gives the following chart:

This data is interesting to get a feel for the risk of running Enterprise Linux 5 Server, but isn't really useful for comparisons with other major versions, distributions, or operating systems -- for example, a default install of Red Hat Enterprise Linux 4AS did not include Firefox, but 5 Server does. You can use our public security measurement data and tools, and run your own custom metrics for any given Red Hat product, package set, timescales, and severity range of interest.


About The Author

Mark J. Cox's picture Red Hat Community Member 25 points

Mark J. Cox

Mark J Cox lives in Scotland and for 2000 to 2018 was the Senior Director of Product Security at Red Hat. Mark has developed software and worked on the security teams of popular open source projects including Apache and OpenSSL. Mark is a founding member of the Apache Software Foundation and the Ope...