Category: security

My favorite yellow press outlet has decided to propagate hearsay instead of writing “original contributions” (but their mastery of creating sensationalistic titles remains unchallenged). This time, they claim that “New features embedded in Cisco IOS like VoIP and Web services can present an opportunity for hackers”.

The only supporting documentation they provide is a story in SearchSecurity with a sensationalistic title (New Cisco IOS bugs pose tempting targets, says Black Hat researcher) followed by two pages of confusion including gems like “… new deployments of Internet Protocol version 6 (IPv6) and VoIP installations may make router exploitation more vulnerable to remote attackers …” supported by “… IPv6 was considered a security threat due to the many net tunnels used to connect to IPv6 …”, which, as anyone who has some basic clue about IPv6 knows, has nothing to do with router vulnerabilities.

Fortunately, Blackhat is a serious undertaking (unlike conferences with grandiose titles like “Cyber Infrastructure Protection”) and provides its presentations online for anyone to see what the presenters were really discussing. I would strongly recommend that you check the excellent “Router Exploitation” presentation by Felix Lindner, which provides a very reasonable analysis of current situation: the routers are exploitable (no surprise there), but it’s very hard to do. Not surprisingly, SNMP is mentioned only once, IPv6 in passing and VoIP only twice (with a good recommendation: don’t run VoIP on your core routers).

Ying would like to have a PE-to-PE IPSec protection for traffic within a single VRF. For example, all traffic in VRF-A sent between PE-1 and PE-2 should be protected with IPSec and the PE-routers should be the endpoints of the IPSec session (CE-to-CE IPSec is trivial).

My first response was “hard to do”, then I started hallucinating about MPLS-over-GRE-over-IPSec-over-IP-over-MPLS tunnels between the PE-routers with tunnel-specific IGP and per-VRF BGP next hops. It can be done (we’ve implemented numerous large-scale MPLS/GRE/IPSec designs), but is there a simpler alternative? Please share your ideas in the comments.

The Cisco Subnet RSS feed I’m receiving from Network World contained interesting information a few days ago: Cisco has reissued the HTTP security advisory from 2005. The 2005 bug was “trivial”: they forgot to quote the “<” character in the output HTML stream as “&lt;” and you could thus insert HTML code into the router’s output by sending pings to the router and inspecting the buffers with show buffers assigned dump (I found the original proof-of-concept exploit on the Wayback Machine). However, I’ve checked the behavior on 12.4(15)T1 and all dangerous characters (“<” and quotes) were properly quoted. So, I’m left with two explanations.

A few days ago, City College of New York hosted the “Cyber Infrastructure Protection Conference”, including a keynote speech by Krishnan Sabnani who described “new class of denial-of-service (DOS) attacks that threaten wireless data networks” … or so the Network World claims in its article.

The conference web site is only accessible through an IP-address-only URL http://134.74.16.84/ (which immediately triggered suspicions in my browser) and the presentations are not available on-line, so I cannot comment on what mr. Sabnani actually told the participants, but the summary provided by Network World is 80% hot air. Here’s their list of “five wireless data network threats outlined by Sabnani”:

Years ago when vendors were pushing the MPLS story to Service Providers, an “independent analyst” wrote a report claiming that MPLS-based VPNs offer security equivalent to Frame Relay networks (to find those reports, ask Google about “MPLS security equivalent to Frame Relay”). This might be true from the functional perspective (and it’s absolutely true that using IP does not make MPLS-based VPNs inherently insecure), but anyone believing these reports might become mightily upset when learning about BGP and MPLS security issues.

Before going any further, please note that exploiting the MPLS architecture as described in All your packets are belong to us presentation requires access to the core SP network, which means that the network (or network management station) has already been successfully penetrated.

A few days ago (the) Steve Bellowin sent an e-mail to the NANOG mailing list pointing to a FUD-full article describing upcoming release of MPLS hacking tools. Christian Koch quickly pointed out a similar presentation given by the same group @ Schmoocon and numerous respondents correctly stated these are old issues … if you’re interested in BGP and MPLS security, of course. Nicolas Fischbach even provided link to a 7 year old presentation describing numerous BGP/IGP/MPLS risks and attack vectors.

When I’ve stumbled across the headline Porn site feud spawns new DNS attack on NetworkWorld’s web site, the urge to read the article was simply irresistible. The article starts with the following paragraph (emphasis mine):

A scrap between two pornographic Web sites turned nasty when one figured out how to take down the other by exploiting a previously unknown quirk in the Internet's DNS.

The link in the paragraph points to another article documenting a completely different DNS attack. The next paragraph contradicts the first one (emphasis yet again mine):

The attack is known as DNS Amplification. It has been used sporadically since December, but it started getting talked about last month when ISPrime, a small New York ISP, started getting hit hard with what's known as a distributed denial of service (DDoS) attack.

Reading an interestingly-titled article on InformIT, I’ve stumbled across the following text:

The survival time is an estimate of how long an un-patched computer will remain uncompromised once it’s connected to the Internet. While the actual time varies, historically it tends to run between 4 and 20 minutes.

This is such an obvious nonsense that I had to check the source, which is also full of alarming messages, but admits at the end that the problems described largely disappeared with XP SP2. Just to put things in perspective: XP SP2 was released in August 2004 and the graph in the alarming blog post displays data from 2008.

Next step: investigate the source of the graph. The »average survival time« is defined as the time between probes on numerous TCP or UDP ports, regardless of whether the port was actually enabled in the workstation and whether the probe was successful or not.

My personal conclusion: as most workstations include some sort of rudimentary firewall these days, the whole approach is bogus. More precisely, it measures an important parameter (average time between probes), but claims it represents something completely different (average survival time). Would you agree with my conclusion?

Lesson learned: Never trust alarming over-simplifying statements based on misunderstood data.

The Network World recently published a story describing the results of an independent security product testing lab, where they’ve discovered (surprise, surprise) that adding security features to Cisco routers “presents a tremendous bottleneck” and “can turn a 60G router into a 5G one or even a 100M bit/sec device”.

The test results haven’t been published yet; I’ve got all the quotes from the NW story, so they might be the result of an ambitious middleware.

We don’t need “independent experts” for that. Anyone who has ever configured VPNs in a high-speed environment can tell you how to kill the performance. The basics are always the same: make sure the dedicated silicon can’t handle the job, so the packets have to be passed to the CPU. Here are a few ideas: