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This time, the Senate

On March 19, I had an opportunity to testify before the Senate Committee on on Commerce, Science, and Transportation. The hearing was entitled Cybersecurity -- Assessing Our Vulnerabilities and Developing An Effective Defense.

I was asked to include information on research problems, educational initiatives, and issues regarding the current state of cyber security in the nation.   As is usual for such things, the time between the invitation and the due date for written testimony was short. Thus, I didn't have the time to delve deeply into the topic areas, but could only address the things that I already had on hand -- including some posts from this blog that I had written before. The result was a little longer than the other statements, but I think I covered more ground.

One hint for people testifying before Congress on such things: you can't depend on how long you will have for spoken remarks, so be sure any points you want to make are in your written testimony. In this case, the hearing was limited to about 75 minutes because there were several votes scheduled on the Senate floor, and the committee needed to adjourn to allow the Senators to attend the votes. And, as is common for too many hearings, there weren't many of the committee members present; I believe the hearing began with only two of the 25 members present, and some movement of members in and out to reach a maximum of four seated at any one time. In this case, the chair (Senator Jay Rockefeller of West Virginia) apologized to us several times for the low turnout. However, many (all?) of the staff and aides were present, so I'm certain the gist of the testimony presented will be considered.Spaf testifying

The Senator made a nice introductory statement.

My written testimony is available on my website as well as the committee site. My oral statement was from rough notes that I modified on the fly as I listened to the other testimony (by Jim Lewis, Eric Weiss and Ed Amoroso). That statement, and the whole hearing, are available via the archived hearing webcast (my remarks start at about 46:30 into the webcast). If I get a transcribed version of those remarks, I will post them along with my written testimony on my website in the "US government" section.

Comments by the other speakers were good overall and I think we collectively covered a lot of ground. The questions from the Senators present indicated that they were listening and knew some of the problems in the area. The comments from Senator Nelson about the intrusions into his systems were surprising: several Senate security staff were present at the hearing and indicated to me that his remarks were the first they had heard of the incidents! So, the hearing apparently set off an incident-response exercise -- separate from responding to my presence in the building, that is. grin

Will this hearing make a difference? I don't know. I've been testifying and saying the same things for over a dozen years (this was my 8th Congressional hearing testimony) and things haven't gotten that much better...and may even be worse. Senator Rockefeller has indicated he intends to introduce legislation supporting more funding for students studying cyber security issues. There was some good news coverage of all this (e.g., FCW and CNet).

I am told that there will be more hearings by this committee. Some House committees have been holding hearings too, and the President's 60 day review continues apace. The added attention is great, but with the sudden interest by so many, the result may be more confusion rather than resolution.

Stay tuned.

As a reminder, if you want to know about my occasional postings such as this but don't want to subscribe to the RSS feed,  you can subscribe to the mailing list.

Also as a reminder, there is my tumble blog on security issues, with links to items on the news and WWW of possible interest to those who find my ramblings and rants of interest.

A Serious Threat to Online Trust

There are several news stories now appearing (e.g., Security News) about a serious flaw in how certificates used in online authentication are validated. Ed Felten gives a nice summary of how this affects online WWW site authentication in his Freedom to Tinker blog posting. Brian Krebs also has his usual readable coverage of the problem in his Washington Post article. Steve Bellovin has some interesting commentary, too, about the legal climate.

Is there cause to be concerned? Yes, but not necessarily about what is being covered in the media. There are other lessons to be learned from this.

Short tutorial

First, for the non-geek reader, I’ll briefly explain certificates.

Think about how, online, I can assure myself that the party at the other end of a link is really who they claim to be. What proof can they offer, considering that I don’t have a direct link? Remember that an attacker can send any bits down the wire to me and may access to faster computers than I do.

I can’t base my decision on how the WWW pages appear, or embedded images. Phishing, for instance, succeeds because the phishers set up sites with names and graphics that look like the real banks and merchants, and users trust the visual appearance. This is a standard difficulty for people—understanding the difference between identity (claiming who I am) and authentication (proving who I am).

In the physical world, we do this by using identity tokens that are issued by trusted third parties. Drivers licenses and passports are two of the most common examples. To get one, we need to produce sufficient proof of identity to a third party to meet its standards of proof. Then, the third party issues a document that is very difficult to forge (almost nothing constructed is impossible to forge or duplicate—but some things require so much time and expenditure it isn’t worthwhile). Because the criteria for proof of identity and strength of construction of the document are known, various other parties will accept the document as “proof” of identity. Of course, other problems occur that I’m not going to address—this USACM whitepaper (of which I was principal author) touches on many of them.

Now, in the online world we cannot issue or see physical documents. Instead, we use certificates. We do this by putting together an electronic document that gives the information we want some entity to certify as true about us. The format of this certificate is generally fixed by standards, the most common one being the X.509 suite. This document is sent to an organization known as a Certificate Authority (CA), usually along with a fee. The certificate authority is presumably well-known, and performs a check (to their own standards) that the information in the document is correct, and it has the right form. The CA then calculate a digital hash value of the data, and creates a digital signature of that hash value. This is then added to the certificate and sent back to the user. This is the equivalent of putting a signature on a license and then sealing it in plastic. Any alteration of the data will change the digital hash, and a third party will find that the new hash and the hash value signed with the key of the CA don’t match. The reason this works is that the hash function and encryption algorithm used are presumed to be so computationally difficult to forge that it is basically not possible.

As an example of a certificate , if you visit “” you can click on the little padlock icon that appears somewhere in the browser window frame (this is browser dependent) to view details of the CERIAS SSL certificate.

You can get more details on all this by reading the referenced Wikipedia pages, and by reading chapters 5 & 7 in Web Security, Privacy and Commerce.

Back to the hack

In summary, some CAs have been negligent about updating their certificate signing mechanisms in the wake of news that MD5 is weak, published back in 2004. The result is that malicious parties can generate and obtain a certificate “authenticating” them as someone else. What makes it worse is that the root certificate of most of these CAs are “built in” to browser and application trust lists to simplify look-up of new certificates. Thus, most people using standard WWW browsers can be fooled into thinking they have connected to real, valid sites—even through they are connecting to rogue sites.

The approach is simple enough: a party constructs two certificates. One is for the false identity she wishes to claim, and the other is real. She crafts the contents of the certificate so that the MD5 hash of the two, in canonical format, is the same. She submits the real identity certificate to the authority, which verifies her bona fides, and returns the certificate with the MD5 hash signed with the CA private key. Our protagonist then copies that signature to the false certificate, which has the same MD5 hash value and thus the same digital signature, and proceeds with her impersonation!

What makes this worse is that the false key she crafts is for a secondary certificate authority. She can publish this in appropriate places, and is now able to mint as many false keys as she wishes—and they will all have signatures that verify in the chain of trust back to the issuer! She can even issue these new certificates using a stronger hash algorithm than MD5!

What makes this even worse is that it has been known for years that MD5 is weak, yet some CAs have continued to use it! Particularly unfortunate is the realization that Lenstra, Wang and de Weger described how this could be done back in 2005. Methinks that may be grounds for some negligence lawsuits if anyone gets really burned by this….

And adding to the complexity of all this is the issue of certificates in use for other purposes. For example, certificates are used with encrypted S/MIME email to digitally sign messages. Certificates are used to sign ActiveX controls for Microsoft software. Certificates are used to verify the information on many identity cards, including (I believe) government-issued Common Access Cards (CAC). Certificates also provide identification for secured instant messaging sessions (e.g., iChat). There may be many other sensitive uses because certificates are a “known” mechanism. Cloud computing services , software updates, and more may be based on these same assumptions. Some of these services may accept and/or use certificates issued by these deficient CAs.


Fixing this is not trivial. Certainly, all CAs need to start issuing certificates based on other message digests, such as SHA-1. However, this will take time and effort, and may not take effect before this problem can be exploited by attackers. Responsible vendors will cease to issue certificates until they get this fixed, but that has an economic impact some many not wish to incur.

We can try to educate end-users about this, but the problem is so complicated with technical details, the average person won’t know how to actually make a determination about valid certificates. It might even cause more harm by leading people to distrust valid certificates by mistake!

It is not possible to simply say that all existing applications will no longer accept certificates rooted at those CAs, or will not accept certificates based on MD5: there are too many extant, valid certificates in place to do that. Eventually, those certificates will expire, and be replaced. That will eventually take care of the problem—perhaps within the space of the next 18 months or so (most certificates are issued for only a year at a time, in part for reasons such as this).

Vendors of applications, and especially WWW browsers, need to give careful thought about updates to their software to flag MD5-based certificates as deserving of special attention. This may or may not be a worthwhile approach, for the reason given above: even with a warning, too few people will be able to know what to do.

Bigger issue

We base a huge amount of trust on certificates and encryption. History has shown how easy it is to get implementations and details wrong. History has also shown how quickly things can be destabilized with advances in technology.

In particular, too many people and organizations take for granted the assumptions on which this vast certificate system is based. For instance, we assume that the hash/digest functions in use are computationally difficult to reverse or cause collisions. We also assume that certain mathematical functions underlying public/private key encryption are too difficult to reverse or “brute force.” However, all it takes is some new insight or analysis, or maybe new, affordable technology (e.g., practical quantum computing, or massively parallel computing) to violate those assumptions.

If you look at the way our systems are constructed, too little thought is given to what happens to existing infrastructure when something breaks. Designs can include compensating and recovery code, but doing so requires some cost in space or time. However, all too often people are willing to avoid the investment by putting off the danger to “if and when that happens.” Thus, we instance such as the Y2K problems and the issues here with potentially rogue CAs.

(I’ll note as an aside, that when I designed the original version of Tripwire and what became the Signacert product, I specifically included simultaneous use of several different message digest functions in different families for this very reason. I knew it was a matter of time before one or two were broken. I still believe that it is beyond reason to find files that will match multiple, different algorithms simultaneously.)

Another issue is the whole question of who we trust, and for what. As noted in the USACM whitepaper, authentication is always relative to a third party. How much do we trust those third parties? How much trust have we invested in the companies and agencies issuing certificates? Are they properly verifying identities? How good is there internal security? How do we know, and how much is at risk from our trust in those entities?

Let me leave you with a final thought. How do we know that this problem has not already been quietly exploited? The basic concept has been in the open literature for years. The general nature of this attack on certificates has been known for well over a decade, if not two. Given the technical and infrastructure resources available to national agencies and organized criminals, and given the motivation to use this hack selectively and quietly, how can we know that it is not already being used?

[Added 12/31/2008]: A follow-up post to this one is available in the blog.


Barack Obama, National Security and Me, Take II

Over the last month or so, many people who read my first post on Senator Obama’s “security summit” at Purdue have asked me about followup, I’ve been asked “Did you ever hear back from the Senator?”, “Has the McCain campaign contacted you?”, and “What do you think about the candidates?” I’ve also been asked by a couple of my colleagues (really!) “Why would they bother to contact you?”

So, let me respond to these, with the last one first.

Why would someone talk with you about policy?

So, I haven’t been elected or served in a cabinet-level position in DC. I haven’t won a Nobel prize (there isn’t one in IT), I’m not in the National Academies (and unlikely to be—few non-crypto security people are), and I don’t have a faculty appointment in a policy program (Purdue doesn’t have one). I also don’t write a lot of policy papers—or any other papers, anymore: I have a persistent RSI problem that has limited my written output for years. However, those aren’t the only indicators that someone has something of value to say.

As I’ve noted in an earlier post, I’ve had some involvement in cyber security policy issues at the Federal level. There’s more than my involvement with the origins of the SfS and Cyber Trust, certainly. I’ve been in an advising role (technology and policy) for nearly 20 years with a wide range of agencies, including the FBI, Air Force, GAO, NSA, NSF, DOE, OSTP, ODNI and more. I’ve served on the PITAC. I’ve testified before Congressional committees a half-dozen times, and met with staff (officially and unofficially) of the Senate and House many times more than that. Most people seem to think I have some good insight into Federal policy in cyber, but additionally, in more general issues of science and technology, and in defense and intelligence.

From another angle, I’ve also been deeply involved in policy. I served on the CRA Board of Directors for 9 years, and have been involved with its government affairs committee for a decade. I’ve been chair or co-chair of the ACM’s US Public Policy committee for a dozen years. From these vantage points I have gained additional insights into technology policy and challenges in a broad array of issues related to cyber, education, and technology.

And I continue to read a lot about these topics and more, including material in a number of the other sciences. And I’ve been involved in the practice and study of cyber security for over 30 years.

I can, without stretching things, say that I probably know more about policy in these areas than about 99.995% of the US population, with some people claiming that I’m in the top 10 or so with respect to broad issues of cyber security policy. That may be why I keep being asked to serve in advisory positions. A lot of people tend to ask me things, and seem to value the advice.

One would hope that at least some of the candidates would be interested in such advice, even if not all of my colleagues (or my family grin are interested in what I have to say.

Have any of the other candidates contacted you?

Simply put—no. I have gotten a lot of mailings from the Republican (and Democratic) campaigns asking me to donate money, but that’s it.

I’m registered as an independent, so that may or may not have played a role. For instance, I can’t volunteer to serve as a poll worker in Indiana because I’m not registered in one of the two main parties! I don’t show up in most of the databases (and that may be a blessing of sorts).

To digress a moment…. I don’t believe either party has a lock on the best ideas—or the worst. I’m not one of those people who votes a straight-ticket no matter what happens. I have friends who would vote for anyone so long as the candidate got the endorsement of “their” party. It reminds me of the drunken football fans with their shirts off in -20F weather cheering insanely for “their” team and willing to fight with a stranger who is wearing the wrong color. Sad. Having read the Constitution and taken the oath to defend it, I don’t recall any mention of political parties or red vs. blue….

That said, I would be happy to talk with any serious candidate (or elected official) about the issues around cyber, security, education, and the IT industry. They are important, and impact the future of our country…and of much of the world.

So, has anyone with the Obama campaign contacted you since his appearance at Purdue?

Well, the answer to this is “yes and no.”

I was told, twice, by a campaign worker that “Someone will call you—we definitely want more advice.” I never got that phone call. No message or explanation why. Nothing.

A few weeks after the second call I did get a strange email message. It was from someone associated with the campaign, welcoming me to some mailing list (that I had not asked to join) and including several Microsoft Word format documents. As my correspondents know, I view sending email with Word documents to be a bad thing. I also view being added to mailing lists without my permission to be a hostile act. I responded to the maintainer of the list and his reply was (paraphrased) “I don’t know why you were added. Someone must have had a reason. I’ll check and get back to you.” Well, I have received no more email from the list, and I never got any followup from that person.

So, in summary, I never got any follow-up from the campaign. I don’t think it is an issue with the Senator (who wouldn’t have been the one to contact me anyhow) but a decision by his staff.

So, depending your level of cynicism, the mentions of my name, of CERIAS, and of follow-up was either (a) a blown opportunity caused by an oversight, or (b) a cynical political ploy to curry local favor.

(My daughter suggested that they are waiting until after the election to appoint me to a lofty position in government. Uh, yeah. That probably explains why I haven’t gotten that MacArthur “genius grant” yet and why Adriana Lima hasn’t called asking me to run away with her—the timing just isn’t right yet. grin

What are your opinions on the Presidential candidates?

I’m not allowed to be partisan in official Purdue outlets. So, in some further posts here over the next week or two I will provide some analysis of both major candidates (NB. Yes, I know there are over 300 candidates for President on the ballots across the country. However, I don’t think there is much chance of Baldwin, Barr, McKinney, Nader, Paul or the rest getting into office. So, I’ll limit my comments to the two main candidates.

If you really want to know who I’m probably voting for, you can see my Facebook page or send me email.

[Update 10/16: After this was published I sent a link to this entry to several people associated with the Obama campaign. Only one responded, and it was clear from his email that there had been a mixup in getting back to me—but no interest in rectifying it.]


Spaf giving testimony to US Congress today

Just a quick note that Eugene Spafford, Executive Director of CERIAS, will be giving testimony this morning at 10 a.m before the House Ways and Means Committee at a “Hearing on Employment Eligibility Verification Systems and the Potential Impacts on SSA’s Ability to Serve Retirees, People with Disabilities, and Workers.” You can view the broadcast live by visiting the hearing’s page and clicking on “Click Here to View Committee Proceedings Live.”