During the creation and review of the list we spent some time to see how closely last years list matched the types of flaws we deal with at Red Hat. We first looked at all the issues that Red Hat fixed across our entire product portfolio in the 2009 calendar year and filtered out those that had the highest severity. All our 2009 vulnerabilities have CVSS scores, so we filtered on those that have a CVSS base score of 7.0 or above^[1].

There were 22 vulnerabilities that matched, and we mapped each one to the most appropriate CWE. This gives us 11 flaw types which led to the most severe flaws affecting Red Hat in 2009:

CWE	CWE Description	CWE/SANS top 25?	Number of Vulnerabilities
CWE-476	NULL Pointer Dereference	No (on cusp)	6
CWE-120	Buffer Copy without Checking Size of Input	Yes	3
CWE-129	Improper Validation of Array Index	Yes	3
CWE-131	Incorrect Calculation of Buffer Size	Yes	3
CWE-78	OS Command Injection	Yes	1
CWE-285	Improper Access Control (Authorization)	Yes	1
CWE-362	Race Condition	Yes	1
CWE-330	Use of Insufficiently Random Values	No (on cusp)	1
CWE-590	Free of Memory not on the Heap	No	1
CWE-672	Use of a Resource after Expiration or Release	No (on cusp)	1
CWE-772	Missing Release of Resource after Effective Lifetime	No (on cusp)	1

10 of the 11 CWE are mentioned in the 2010 CWE/SANS document, although 4 of them are on "the cusp" and didn't make it into the top 25.

This quick review shows us that 2009 was the year of the kernel NULL pointer dereference flaw, as they could allow local untrusted users to gain privileges, and several public exploits to do just that were released. For Red Hat, interactions with SELinux prevented them being able to be easily mitigated, until the end of the year when we provided updates. Now, in 2010, the upstream Linux kernel and many vendors ship with protections to prevent kernel NULL pointers leading to privilege escalation. So although 2009 was the year where CWE-476 mattered to Linux administrators, it didn't make the SANS/CWE top 25 as this flaw type should not lead to severe issues (as long as the protections remain sufficient).

Here is a breakdown with the complete data set to show the CVSS scores and packages affected:

CVE	CWE	top 25?	CVSS base	Fixed in
CVE-2008-5182	CWE-362	Yes	7.2	Red Hat Enterprise Linux 5 (kernel)
CVE-2009-0065	CWE-129	Yes	8.3	Red Hat Enterprise Linux 4,5,MRG (kernel)
CVE-2009-0692	CWE-120	Yes	8.3	Red Hat Enterprise Linux 3,4 (dhcp)
CVE-2009-0778	CWE-772	No (on cusp)	7.1	Red Hat Enterprise Linux 5 (kernel)
CVE-2009-0846	CWE-590	No	9.3	Red Hat Enterprise Linux 2.1, 3 (krb5) [2]
CVE-2009-1185	CWE-131	Yes	7.2	Red Hat Enterprise Linux 5 (udev)
CVE-2009-1385	CWE-129	Yes	7.1	Red Hat Enterprise Linux 3,4,5,MRG (kernel)
CVE-2009-1439	CWE-131	Yes	7.1	Red Hat Enterprise Linux 4,5,MRG (kernel)
CVE-2009-1579	CWE-78	Yes	7.5	Red Hat Enterprise Linux 3,4,5 (squirrelmail)
CVE-2009-1633	CWE-131	Yes	7.1	Red Hat Enterprise Linux 4,5,MRG (kernel)
CVE-2009-2406	CWE-120	Yes	7.2	Red Hat Enterprise Linux 5 (kernel)
CVE-2009-2407	CWE-120	Yes	7.2	Red Hat Enterprise Linux 5 (kernel)
CVE-2009-2692	CWE-476	No (on cusp)	7.2	Red Hat Enterprise Linux 3,4,5,MRG (kernel)
CVE-2009-2694	CWE-129	Yes	7.5	Red Hat Enterprise Linux 3,4,5 (pidgin)
CVE-2009-2698	CWE-476	No (on cusp)	7.2	Red Hat Enterprise Linux 3,4,5 (kernel)
CVE-2009-2848	CWE-672	No (on cusp)	7.2	Red Hat Enterprise Linux 3,4,5,MRG (kernel)
CVE-2009-2908	CWE-476	No (on cusp)	7.2	Red Hat Enterprise Linux 5 (kernel)
CVE-2009-3238	CWE-330	No (on cusp)	7.8	Red Hat Enterprise Linux 4,5,MRG (kernel)
CVE-2009-3290	CWE-285	Yes	7.2	Red Hat Enterprise Linux 5 (kvm)
CVE-2009-3547	CWE-476	No (on cusp)	7.2	Red Hat Enterprise Linux 3,4,5,MRG (kernel)
CVE-2009-3620	CWE-476	No (on cusp)	7.2	Red Hat Enterprise Linux 4,5,MRG (kernel)
CVE-2009-3726	CWE-476	No (on cusp)	7.2	Red Hat Enterprise Linux 5,MRG (kernel)

[1] NIST NVD rate vulnerabilities as "High" severity if they have a CVSS base score of 7.0-10.0. This ends up excluding flaws in web browsers such as Firefox which can have a maximum CVSS base score of 6.8.

[2] Red Hat Enterprise Linux 4 and 5 were also affected by this vulnerability, but with a lower CVSS base score of 4.3, due to the extra runtime pointer checking.

The stories center around how open source software such as Firefox was able to produce updates to correct this issue just a few days after the Blackhat conference, while Microsoft still hasn't fixed it and are "investigating a possible vulnerability in Windows presented during Black Hat".

But the actual timeline is missing from these stories.

The NULL character certificate flaw (CVE-2009-2408) was actually disclosed by two researchers working independantly who both happened to present the work at the same conference, Blackhat, in July this year. Dan Kaminsky mentioned it as part of a series of PKI flaws he disclosed. Marlinspike had found the same flaw, but was able to demonstrate it in practice by managing to get a trusted Certificate Authority to sign such a malicious certificate.

The flaw was no Blackhat surprise; Dan Kaminsky actually found this issue many months ago and responsibly reported the issues to vendors including Red Hat, Microsoft, and Mozilla. We found out about this issue on 25th February 2009 and worked with Dan and some of the upstream projects on these issues in advance, so we had plenty of time to prepare updates and this is why we were able to have them ready to release just after the disclosure.

We keep all our friends and family contacts in a single text file in vCard format. We sync this file to our phones (mobile and house DECT phones) and home automation system (for caller ID and phone book). I also print out a copy to take when travelling. Except I rarely print out an update as I've failed to find any useful program to pretty print the contacts. Previously I used a quick hack script in perl to convert the vcard entries to HTML, but it wasn't clever enough to handle page breaks and needed manual setting all the margins and page sizes correctly. I like to print it to fit in my paper planner, a Compact size Franklin Covey planner system.

I've been using Scribus for a few months, mostly for our wedding invites and stationary, and spotted that Scribus had a Python API. So a few hours later and out has popped a Python script you can use to pretty print a vCard vcf file, handling page breaks, images, and large margins to skip the hole punches.

Here is an extract from a sample vCard file:

BEGIN:VCARD
ADR;TYPE=work:;;10 Downing Street;London;SW1A 2AA
TEL;TYPE=fax:+44 2079 250918
NICKNAME:Prime Minister
FN:Gordon Brown
N:Brown;Gordon
PHOTO;VALUE=URI:http://www.number10.gov.uk/wp-content/uploads/pm-official-pic-234x300.jpg
VERSION:3.0
END:VCARD

You'll need a few things:

1. a sample vCard file or your own one
2. vcf2scribus.py script (version 1.0)
3. A recent version of Scribus. 1.3.5 works, but earlier ones will not.
4. You'll also need the python vobject library installed if you haven't already got it

Use the "Script" "Execute Script" option, find and select vcf2scribus.py and hopefully you'll end up with something like this:

You can then save it as a pdf or print it direct.

The script is a bit of a hack and has hard-coded page sizes, fonts, margins, vcard sections used, and so on. But I figure it might save someone a couple of hours and only needs a bit of modification to suit. It would be fairly easy to extend the script to use the Scribus API to let folks select the vcard file, page sizes, fonts, and things. Bonus points if you fix it to figure out the final sizes of the images and right align them. This is my second ever python program so no sniggering at the code!

Errata count

The chart below illustrates the total number of security updates issued for Red Hat Enterprise Linux 5 Server as if you installed 5.3, up to and including the 5.4 release, broken down by severity. I've split it 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 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 you have installed or removed.

So for a default install, from release of 5.3 up to and including 5.4, we shipped 51 advisories to address 166 vulnerabilities. 8 advisories were rated critical, 18 were important, and the remaining 25 were moderate and low.

Or, for all packages, from release of 5.3 to and including 5.4, we shipped 78 advisories to address 251 vulnerabilities. 9 advisories were rated critical, 28 were important, and the remaining 41 were moderate and low.

Critical vulnerabilities

The 9 critical advisories were for just 3 different packages. In all the cases below, given the nature of the flaws, ExecShield protections in RHEL5 should make exploiting these memory flaws harder.

1. Seven updates to Firefox (February, March 4th, March 27th, April 21st, April 27th, June, July ) where a malicious web site could potentially run arbitrary code as the user running Firefox.
2. An update to kdelibs (June), where a malicious web site could potentially run arbitrary code as the user running the Konqueror browser. kdelibs is not a default installation package.
3. An update to the NSS library (July), where a service could present a malicious SSL certificate causing a heap overflow which could potentially run arbitrary code as the user running a browser such as Firefox.

Updates to correct all of these critical vulnerabilities were available via Red Hat Network either the same day, or up to one calendar day after the issues were public.

In fact for Red Hat Enterprise Linux 5 since release and to date, every critical vulnerability has had an update available to address it 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 several NULL pointer dereference kernel issues. NULL pointer dereference flaws in the Linux kernel can often be easily abused by a local unprivileged user to gain root privileges through the mapping of low memory pages and crafting them to contain valid malicious instructions:

• CVE-2009-2698 was public on August 24th and a working privilege escalation exploit was published about a week later. This issue was addressed for Red Hat Enterprise Linux 5 by a kernel update on August 24th.
• CVE-2009-2692 was public on August 13th and a working privilege escalation exploit was published the same day. This issue was addressed for Red Hat Enterprise Linux 5 by a kernel update on August 24th.
• CVE-2009-1897 was public on July 16th along with a working privilege escalation exploit. This issue affected only beta versions of the Red Hat Enterprise Linux 5.4 kernel and it was addressed prior to the release of Red Hat Enterprise Linux 5.4.

Red Hat Enterprise Linux since 5.2 has contained backported patches from the upstream Linux kernel to add the ability to restrict unprivileged mapping of low memory, designed to mitigate NULL pointer dereference flaws. However it was found that this protection was not sufficient, as a system with SELinux enabled is more permissive in allowing local users in the unconfined_t domain to map low memory areas even if the mmap_min_addr restriction is enabled. This is CVE-2009-2695 and will be addressed in a future kernel update.

Mitigations

Red Hat Enterprise Linux 5 shipped with a number of security technologies designed to make it harder to exploit vulnerabilities and in some cases block exploits for certain flaw types completely. From 5.3 to 5.4 there were three flaws blocked that would otherwise have required critical updates:

• CVE-2009-0692, a stack buffer overflow flaw in dhclient. FORTIFY_SOURCE protection detects the overflow and causes dhclient to exit with no security consequence. No security update for users of Red Hat Enterprise Linux 5 was needed.
• CVE-2009-1252 a buffer overflow flaw in NTP caught by FORTIFY_SOURCE. We issued an update as a remote attacker could still cause a denial of service.
• CVE-2009-0846, a uninitialized pointer free in krb5. glibc provides a hardened malloc/free implementation which mitigates the exploitability of this flaw, however we issued an update as a remote attacker could still cause a denial of service.

Previous updates

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

See also: 5.2 to 5.3, 5.1 to 5.2, and 5.0 to 5.1 risk reports.

MD2 signature verification

The first issue is that many web browsers still accept certificates with MD2 hash signatures, even though MD2 is no longer considered a cryptographically strong algorithm. This could make it easier for an attacker to create a malicious certificate that would be treated as trusted by a browser. It turns out that there are not many valid MD2 hash certificates around any more, and the main one that does exist is at the trusted root level anyway (and there is actually no need for a crypto library to verify the self-signature on a trusted root). So most vendors have chosen to address this issue by disabling MD2 completely for certificate verification. This is allocated CVE name CVE-2009-2409 ( single name for all affected products).

• OpenSSL. For upstream OpenSSL we have disabled MD2 support completely. This was done in two stages; the first was a patch in June 2009 that removed the redundant check of a trusted root self-signed certificate. Then in July, MD2 was totally disabled. So this issue does not affect OpenSSL 1.0.0 beta 3 or later. Although there have not yet been an upstream release of 0.9.8 containing this fix, a future OpenSSL 0.9.8 (after 0.9.8k) will disable MD2, probably in a few weeks.

• GnuTLS. The upstream GnuTLS library has for some time meant to have disabled MD2 support, although due to a broken patch it wasn't actually disabled correctly until January 2009. So this issue does not affect GnuTLS versions 2.6.4 and above, or GnuTLS versions 2.7.4 and above.

• NSS (and hence Firefox). The upstream NSS library since version 3.12.3 (April 2009) has disabled MD2 and MD4 by default (although legacy applications could turn it back on using an environment variable "NSS_ALLOW_WEAK_SIGNATURE_ALG" if they need to). Mozilla Firefox since version 3.5 has used this NSS version and therefore MD2 is disabled. I suspect this issue will get addressed in a future Firefox 3.0 update in the future too if they rebase to the new NSS.

There is no immediate panic to address this issue as a critical security issue, as in order for it to be exploited an attacker still has to create a MD2 collision with this root certificate; something that is as of today still a significant amount of effort.

My CVSS v2 base score for CVE-2009-2409 would be 2.6 (AV:N/AC:H/Au:N/C:N/I:P/A:N)

Differences in Common Name handling

This issue is about how Common Names are checked for validity by applications. For example if a server presents a certificate with two CN entries, how does the app validate those. Does it use the first one, the last one, or all of them?

• OpenSSL. OpenSSL provides an API that allow applications to check CN names any way they want. It turns out that, without sound guidance, applications have tended to do things differently. A summary of a few OpenSSL applications is in this Red Hat bugzilla comment. But as a CA should validate all CN names in a certificate being signing, these are really just bugs and do not have a security impact

Leading 0's in Common Name handling

The second issue is all about inconsistencies in the interpretation of subject x509 names in certificates. Specifically "issue 2b, subattack 1" is where a malicious certificate can contain leading 0's in the OID. The idea is that an attacker could add in some OID into a certificate that, when handled by the Certificate Authority, would appear to be some extension and ignored, but when handled by OpenSSL would appear to be the Common Name OID. So the attacker would present the certificate to a client application and it might think that the OID is actually a Common Name, and accept the certificate where it otherwise should not.

• OpenSSL. This is not a security issue for OpenSSL. Steve Henson explains: "OpenSSL does tolerate leading 0x80 but it does _not_ recognize this as commonName because the NID code checks for a precise match with the encoding. Attempts to print this out will never show commonName nor will attempts to look up using NID_commonName". However this will be addressed as a bug fix in the future.

• NSS (and hence Firefox). NSS is noted in the paper as having a similar issue, but again it's not fooled into treating the OID as a Common Name so this is not a security issue (and therefore I didn't check if this is already fixed in the new upstream NSS).

OID overflow in Common Name handling

"issue 2b, subattack 2" is where a malicious certificate can have a very large integer in the OID. The idea is that an attacker could add in some OID into a certificate that, when handled by the CA, would appear to be some extension and ignored, but when handled by OpenSSL would overflow and appear to be the Common Name OID. So the attacker would present the certificate to a client application using OpenSSL and it might think that the OID is actually a Common Name, and accept the certificate where it otherwise should not.

• OpenSSL. This issue was actually fixed upstream in September 2006 in OpenSSL 0.9.8d by switching to using the bignum library for handling the OID. Even for older versions though it's really not a security issue for the same reason as given earlier: the OpenSSL NID code checks for a precise match with the encoding. So attempts to print this out will never show it being a Common Name, nor will attempts to look it up as a Common Name succeed.

NULL bytes in Common Name handling

"issue 2, attack 2c" is regarding NULL terminators in a Common Name field. If an attacker is able to get a carefully-crafted certificate signed by a Certificate Authority trusted by a browser, the attacker could use the certificate during a man-in-the-middle attack and potentially confuse the browser into accepting it by mistake.

• NSS (and hence Firefox). This issue affected NSS and is assigned CVE-2009-2408. The upstream NSS library since version 3.12.3 (April 2009) has fixes to address this issue. Therefore Firefox 3.5 is not affected.

My CVSS v2 base score for CVE-2009-2408 would be 4.3 (AV:N/AC:M/Au:N/C:N/I:P/A:N)

OpenSSL 'compat mode' subject name injection

"issue 2d" is how the OpenSSL command line utility will output unescaped subject X509 lines to standard output. So if some utility runs the openssl application from the command line and parses the text output, and if an attacker can craft a malicious certificate in such a way they fool a CA into signing it, they could present it to the utility and possibly fool that utility into thinking fields were different to what they actually are, perhaps allowing the certificate to be accepted as legitimate.

• OpenSSL. This attack requires that some utility will parse the output of OpenSSL command line using the default 'compat' mode. Applications should never do this. Upstream OpenSSL are unlikely to address this issue directly, although in the future the default output mode perhaps could be changed to something other than 'compat', and it's likely a documentation update will remind users that parsing the output of running such an openssl command is not the right way to use OpenSSL.

OpenSSL ASN1 printing crash

• OpenSSL. This was reported by Dan to OpenSSL and fixed in March 2009. This was allocated CVE name CVE-2009-0590. Therefore OpenSSL 0.9.8k and later contains a fix for this issue.

My CVSS v2 base score for CVE-2009-0590 would be 2.6 (AV:N/AC:H/Au:N/C:N/I:N/A:P)

Last winter the Red Hat video team came to my house to record some footage for both internal and external use. On one of the internal videos they look at my home automation system, point the camera at a wall tablet, and figure out that I'd not used my treadmill in over two years. So there were really two options (1) remove the year from the display so it would never look like we were slacking for more than a year, or (2) find a way to get motivated again.

Recently we both started using Twitter, so it seemed like a natural progression to hook the treadmill to twitter and have it publicly embarrass us for slacking off.

So the treadmill now has it's own twitter page.

We called it 'twedmill' ('tweadmill' perhaps is more correct, but just sounds like a factory that weaves twead jackets). Here is how it works:

The treadmill itself is pretty standard; it's from Trimline and has a fancy computer. When I looked inside and saw a PIC I was tempted to interface direct to the computer, but didn't really have the time to get around to that. Although the treadmill does things like have a variable incline and measurement of heart rate, all I really care about it making sure we were using it, for how long, and how far we got.

Under a cover in the base are the PWM controllers, motors, and the belt drive to the treadmill deck. The treadmill itself measures the belt speed by having a single magnet on the wheel and a small sensor next to it, one revolution giving one pulse. So to keep things simple I just hot-glued a spare reed switch I had around so the same magnet would trigger it. The reed switch happily copes with the treadmill even on top speed, so no real need for anything more fancy.

I didn't have anything that could accurately measure the diameter of the roller, so by counting pulses at various speeds and comparing to the onboard display it worked out at 8122 pulses/revolutions per (uk) mile (so that's about 198mm of travel per pulse, making the diameter of the roller about 63mm).

I use a 1-wire network in the house to measure temperatures, watch the doorbell, and control the central heating system, so I wanted to use the same system to deal with the treadmill. So the reed switch connects to a DS2423 counter (Unfortunately it seems the DS2423 is discontinued now). The DS2423 was only available in a surface-mount package, so I found some converters on ebay to save having to design a PCB just for three components. The DS2423 connects into a 1-wire hub in node0, then to a 1-wire USB adapter on our main server, currently running Fedora 10.

The software used in based on the source code from 'digitemp' as it includes code in cnt1d.c to read the counter values. Every ten seconds the jabber treadmill bot switches to the right network segment on the 1-wire hub then polls the counter of the DS2423 to see if the treadmill has moved. Once the treadmill has stopped moving for a while the software stores the total distance travelled and time in a database, sends an email, and uses the perl Net::Twitter module to post a mesage to twitter. (It can also draw a graph showing speed over time, but that turned out to be not very interesting)

For the future I'd quite like to hook directly into the treadmill computer, perhaps giving two way control of the treadmill programs, as well as recording the incline and heart rate. Another idea has been to use the current treadmill speed to decide which music video to play next based on bpm (the tv is connected to an old XBOX running XMBC so could easilly be remotely controlled to switch videos). Or perhaps link it to google streets for a virtual jog through some random town. Finally, you currently have to select who is using the treadmill before (or very quickly after) using it using the touch panels in the house; which seems like a good excuse to play with some RFID in our shoes, perhaps also using that to select a playlist of music videos per person.

I also recently bought a new phone, a HTC Touch HD, to replace my aging Mio A701. Although it has a Windows OS, it doesn't force you to use ActiveSync and you can set it to instead appear as a card reader when plugged in via USB.

It got me wondering if the Asus would boot from the phone. It does:

The phone comes with a 8Gb microSD card so plenty of room for the Fedora image without disturbing the other phone software, pictures, and so on. I just used the Live image creator to write the image to the microSD card, made it bootable, put it into the phone and set the phone to card reader mode. Now every time the phone is plugged in into a PC it appears to be just a bootable USB stick with Fedora live image installed. All I need now is a small retractable USB cable and then there is no need to carry around the separate MicroSD card (or a USB stick)

Actually this isn't surprising and is exactly what I'd expect; it's all down to third party applications.

Let's say you're browsing the web. It's more than likely that at some point you'll want to view some PDF files, watch some Flash content, or play a Java game. Those tasks are all dealt with by third party applications, although to the end user it's all part of the browser experience. Since your system is only as secure as its weakest link, you need to manage security updates for those third party applications just as carefully as you manage security updates for the rest of your system. That's why Adobe Reader, Java, Flash, and all the myriad of other applications you've installed in order to make your system useful have their own update mechanisms. Some applications on Windows will 'phone home' when they are run and check to see if they need to be updated, others deploy services that sit in the background looking for updates from time to time, others even check every time your system starts. Many don't get automated updates at all.

How do you deal with all that risk? I believe it's possible by providing an OS distribution which includes all the bits you'll likely need to make a useful computing environment, thereby taking away that update uncertainty. Red Hat ship several PDF viewers in our distributions for example, but we also ship (in an Extras channel) Adobe Reader. Our Security Response Team are monitoring for security issues in everything we ship, all the third party applications, and providing a single point of contact, a single notification system, and a single way to get the updates.

If Microsoft knew that say 25% of all their users installed Firefox, wouldn't they be better bundling it and providing their centralised automated updates for it, to reduce their customers overall risk? They do already bundle some third party applications, although it's been with mixed success as we found 3 years ago when they didn't provide security fixes for bundled Flash (ZDNet coverage).

This is, in part, why you've not seen me respond recently to the Vista security reports which compare vulnerability counts. In these reports they use a cut-down minimal Red Hat Enterprise Linux installation in order to make it look more like Windows for the comparisons. But this is completely backwards -- the fact that we're including and fixing the flaws using a common process in so much third party software is actually helping reduce the risk and protect real customers. For example we could easily cut our vulnerability count by shipping only one PDF viewer instead of four. But if we know that these other viewers are going to get installed by the customer anyway all we've done is to hide the vulnerability count elsewhere, and you've made the customers overall risk increase.

So it may seem counter-intuitive but we should ship as much third party applications (that we know people use) as we can, because a single managed security update and notification process will decrease a users overall risk. The fewer third party applications that users have to get from elsewhere and install and manage for themselves the better in my opinion.

There are plenty of new products to come, so we're currently hiring for another engineer to join the response team. The full job details are here:

https://redhat.ats.hrsmart.com/cgi-bin/a/highlightjob.cgi?jobid=3685

Although the location is specified as the Czech Republic there is actually no specific restriction on the location of this position, and the candidate could be located at any one of the world-wide Red Hat offices, or potentially even remote.

If you are interested please submit your resume through the online application process, or feel free to mail me with questions.

CVSS v2 Base Score 6.5 (AV:N/AC:L/Au:S/C:P/I:P/A:P)

This is really a moderate severity flaw because you need a remote attacker who has the ability to start/stop/control ZoneMinder, and you really should protect your ZoneMinder installation so you don't allow arbitrary people to control your security system. (Although I think at least one distributor package of ZoneMinder doesn't protect it by default, and you can find a few unprotected ZoneMinder consoles using a web search).

I discovered this because when we went on holiday early in April I forgot to turn down the heating in the house. Our heating system is controlled by computer and you can change the settings locally by talking to a Jabber heating bot (Figure 1). But remotely over the internet it's pretty locked down and the only thing we can access is the installation of ZoneMinder. So without remote shell access, and with an hour to spare at Heathrow waiting for the connecting flight to Phoenix, I figured the easiest way to correct the temperature was to find a security flaw in ZoneMinder and exploit it. The fallback plan was to explain to our house-minder how to change it locally, but that didn't seem as much fun.

So I downloaded ZoneMinder and took a look at the source. ZoneMinder is a mixture of C and PHP, and a few years ago I found a buffer overflow in one of the C CGI scripts, but as I use Red Hat Enterprise Linux exploiting any new buffer overflow with my ZoneMinder compiled as PIE definately wouldn't be feasible with just an hours work. My PHP and Apache were up to date too. So I focussed on the PHP scripts.

A quick grep of the PHP scripts packaged with ZoneMinder found a few cases where the arguments passed to PHP exec() were not escaped. One of them was really straightforward to exploit, and with a carefully crafted URL (and if you have authorization to a ZoneMinder installation) you can run arbitrary shell code as the Apache httpd user. So with the help of an inserted semicolon and one reverse shell I had the ability to remotely turn down the heating, and was happy.

I notified the ZoneMinder author and the various vendors shortly after and updates were released today (a patch is also available)

Figure 1: Local heating control

Hi! I'm Mark Cox. This blog gives my thoughts and opinions on my security work, open source, fedora, home automation, and other topics.

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