Matt Blaze's
Science, Security, Curiosity
Archives: 26 June 2007 - 24 January 2008

Bell System Secrecy of Communications poster A recurring theme in this blog over the last year has been how the sweeping surveillance technology envisioned by the 2007 US Protect America Act introduces fundamental technical vulnerabilities into the nation's communications infrastructure. These risks should worry law enforcement and the national security community at least as much as they worry civil liberties advocates. A post last October mentioned an analysis that I was writing with Steve Bellovin, Whit Diffie, Susan Landau, Peter Neumann and Jennifer Rexford.

The final version of our paper, "Risking Communications Security: Potential Hazards of the Protect America Act," will be published in the January/February 2008 issue of IEEE Security and Privacy, which hits the stands in a few weeks. But you can download a preprint of our article today at [PDF]. Remember, you saw it here first.

This week the Senate takes up whether to make the warrantless wiretapping act permanent, so the subject is extremely timely. The technical risks created by unsupervised wiretapping on this scale are enormously serious (and reason enough to urge Congress to let this misguided law expire). But safety and security may be subordinated in the debate to more entrenched interests. In particular, AT&T and other communications carriers have been lobbying hard for an amendment that gives them retroactive immunity from any liability they might have had for turning over Americans' communications and call records to the government, legally or not, before the act passed.

As someone who began his professional career in the Bell System (and who stayed around through several of its successors), the push for telco immunity represents an especially bitter disillusionment for me. Say what you will about the old Phone Company, but respect for customer privacy was once a deeply rooted point of pride in the corporate ethos. There was no faster way to be fired (or worse) than to snoop into call records or facilitate illegal wiretaps, well intentioned or not. And it was genuinely part of the culture; we believed in it, even those of us ordinarily disposed toward a skeptical view of the official company line. Now it all seems like just another bit of cynical, focus-group-tested PR.

Apologies to David Byrne for paraphrasing his hauntingly prescient lyrics. And thanks to Eric Cronin for discovering and scanning the now sadly nostalgic reminder reproduced at right.

I've dabbled with photography for most of my life, defiantly regressing toward bulkier equipment and more cumbersome technique as cameras become inexorably smaller and easier to use with each successive generation. Lately, I've settled on a large format camera with a tethered digital scanning back, which is about as unwieldy as I'd likely want to endure, at least without employing a pack mule.

But for all the effort I'm apparently willing to expend to take pictures, I'm pathologically negligent about actually doing anything with them once they've been taken. Scattered about my home and office are boxes of unprinted negatives and disk drives of unprocessed captures (this is, admittedly, overwhelmingly for the best). So it was somewhat against my natural inclinations that a few years ago I started making available an idiosyncratic (that is to say, random) selection of images elsewhere on this web site.

Publishing photos on my own server has been a mixed bag. It maximizes my control over the presentation, which appeals to the control freak in me, but it also creates lot of non-photographic work every time I want to add a new picture -- editing html, creating thumbnails, updating links and indexes. I've got generally ample bandwidth, but every now and then someone hotlinks into an image from some wildly popular place and everything slows to a crawl. I could build better tools and install better filters to fix most of these shortcomings, but, true to my own form I suppose, I haven't. So a few weeks ago I finally gave in to the temptations of convenience and opened an account on Flickr.

I'm slowly (but thus far, at least, steadily) populating my Flickr page with everything from casual snapshots to dubiously artistic abstractions. It's still an experiment for me, but a side effect has been to bring into focus (sorry) some of what's good and what's bad about how we publish on the web.

Flickr is a mixed bag, too, but it's different mix than doing everything on my own has been. It's certainly easier. And there's an appeal to being able easily link photos into communities of other photographers, leave comments, and attract a more diverse audience. So far at it seems not to have scaled up unmanageably or become hopelessly mired in robotic spam. They make it easy to publish under a Creative Commons license, which I use for most of my pictures. But there are also small annoyances. The thumbnail resizing algorithm sometimes adds too much contrast for my taste -- I'd welcome an option to re-scale certain images myself. The page layout is inflexible. There's no way to control who can view (and mine data from) your social network. And they get intellectual property wrong in small but important ways. For example, every published photo is prominently labeled "this photo is public", risking the impression that copyrighted and CC-licensed photos are actually in the public domain and free for any use without permission or attribution.

I wonder how most people feel about that; do we think of our own creative output, however humble, as being deserving of protection? Or do we tend to regard intellectual property as legitimately applying only to "serious" for-profit enterprises (with Hollywood and the music industry rightfully occupying rarefied positions at the top of the socio-legal hierarchy)? A couple of years ago I led a small discussion group for incoming students at my overpriced Ivy-league university. The topic was Larry Lessig's book Free Culture, and I started by asking what I thought was a softball question about who was exclusively a content consumer and who occasionally produced creative things deserving protection and recognition. To my surprise, everyone put themselves squarely in the former category. These were talented kids, mostly from privileged background -- hardly a group that tends to be shy about their own creativity. Maybe it was the setting or maybe it was how I asked. But perhaps their apparent humility was symptomatic of something deeply rooted in our current copyright mess. Until we can abandon this increasingly artificial distinction -- "consumers" and "content producers", us against them -- our lopsided copyright laws seem bound to continue on their current draconian trajectory, with public disrespect for the rules becoming correspondingly all the more flagrant.

Today Ohio Secretary of State Jennifer Brunner released the results of a comprehensive security review of the electronic voting systems used in her state. The study was similar in scope to the California top-to-bottom review conducted this summer (with which I was also involved), covering the systems used in Ohio. The project contracted several academic teams and others to examine the election procedures, equipment and source code used in that state, with the aim of identifying any problems that might render elections vulnerable to tampering under operational conditions.

The ten-week project examined in detail the touch-screen, optical scan, and election management technology from e-voting vendors ES&S, Hart InterCivic and Premier Election Systems (formerly Diebold). Project PI Patrick McDaniel (of Penn State) coordinated the academic teams and led the study of the Hart and Premier Systems (parts of which had already been reviewed in the California study). Giovanni Vigna (of WebWise Security and UCSB) led the team that did penetration testing of the ES&S system.

I led the University of Pennsylvania-based team, which examined the ES&S source code. This was particularly interesting, because, unlike Hart and Premier, the full ES&S source code suite hadn't previously been studied by the academic security community, although ES&S products are used by voters in 43 US states and elsewhere around the world. The study represented a rather unique opportunity to contribute to our understanding of e-voting security in practice, both inside and outside Ohio.

My group -- Adam Aviv, Pavol Cerny, Sandy Clark, Eric Cronin, Gaurav Shah, and Micah Sherr -- worked full-time with the source code and sample voting machines in a secure room on the Penn campus, trying to find ways to defeat security mechanisms under various kinds of real-world conditions. (Our confidentiality agreement prevented us from saying anything about the project until today, which is why we may have seemed especially unsociable for the last few months.)

As our report describes, we largely succeeded at finding exploitable vulnerabilities that could affect the integrity of elections that use this equipment.

The report is long and detailed, and speaks for itself far better than I can here. A brief statement from Patrick McDaniel and me can be found (PDF format) here. Our full 334 page report can be downloaded (11MB, PDF format) from the Ohio Secretary of State's web site at .

There were other parts to the study (called "Project EVEREST") than just the source code analysis, and, of course, there is also the question of how to actually secure elections in practice given the problems we found. The Ohio Secretary of State's web site [link] has a nice summary of the review and of the Secretary's recommendations.

Addendum (4 June 2008): Apparently the Ohio SoS web site was recently reorganized, breaking the original links in this post. I've updated the links to point to their new locations.

Addendum (24 March 2009): See this post for a recent case of vote stealing that exploited a user-interface flaw in the ES&S iVotronic.

Most of the debate surrounding the Protect America Act -- hastily passed this summer and eliminating requirements for court orders for many kinds of government wiretaps -- has focused on the perceived need to balance national security against individual privacy. And while it's surely true that wiretap policy strikes at the heart of that balance, the specter of unrestrained government spying may not be the the most immediate reason to fear this ill-conceived and dangerous change in US law. Civil liberties concerns aside, the engineering implications of these new wiretapping rules, coupled with what we can discern about how they are being implemented, should be at least as unsettling to hawks as to doves.

My colleagues Steve Bellovin, Whit Diffie, Susan Landau, Peter Neumann, Jennifer Rexford and I just completed a brief analysis of the Protect America Act from the networking, surveillance and security engineering perspective. Our draft technical report, Risking Communications Security: Potential Hazards of the "Protect America Act" can be found at [pdf format].

Update 10/13/07: A less-technical version can be found at [pdf format].

Update 10/22/07: A new (and slighty less drafty) draft of the full technical report is now online, at [pdf format].

This morning the Electronic Frontier Foundation will be releasing the first installment of many hundreds of scanned pages concerning the FBI's DCS-3000 surveillance Data Collection System. Most of the documents, which were obtained through a Freedom of Information Act (FOIA) lawsuit filed by the EFF, are heavily (almost laughably) redacted user manuals and internal FBI memos, with many pages almost entirely devoid of text. Nonetheless, what remains provides a rare, if fragmented and cryptic, glimpse of the state of FBI surveillance technology in general and CALEA wiretapping in particular.

Ryan Singel has a nice summary of the documents in his article on Wired's web site. It will take time to digest the huge volume of incomplete and jargon-laden material in the documents, but interesting tidbits emerge even from a cursory reading.

Contrary to previous speculation, DCS-3000 is much more than an updated version of the FBI's Carnivore Internet interception and collection device first disclosed seven years ago. Instead, the DCS system appears to be a comprehensive software suite for managing and collecting data from a variety of Title III (law enforcement) surveillance technologies, including Internet wiretaps, wireline voice telephony, cellular, "push-to-talk", and maybe others. The system provides a single interface for managing and collecting evidence from all the different kinds of wiretaps the FBI uses, connected via a "DCSNet" for getting tapped traffic to any FBI field office in the US. There are references to several other FBI systems as well, most notably the Bureau's ill-fated Trilogy case management system, and also something called DCS-5000, which is described as an analogous system for managing FISA (national security) taps. The software is definitely large and complex -- there are mentions of multi-week training courses for the agents who use it.

That complexity itself raises some difficult security questions. As my colleague Steve Bellovin points out, the new documents suggest that the FBI may have failed to adequately secure the system against an insider threat. But aside from the usual risks that the software could be subverted or abused, in a wiretapping system there's also the problem of ensuring that intercepted evidence is faithfully recorded. And that, it turns out, can be harder than it sounds.

Two years ago, my graduate students and I discovered basic flaws in the in-band signaling mechanisms used for many years in older analog voice telephone wiretaps. The flaws allow a wiretap target to interfere with a phone tap by playing special tones that cause interception equipment to shut down prematurely or record misleading call data. We speculated, based on the documents available to us then, that the CALEA-based interception system now used by the FBI might suffer from similar problems. The FBI denied this at the time, claiming that only a few systems remain vulnerable to our attacks. But sure enough, the EFF's new documents refer in several places to continued support for in-band "C-tone" signaling in voice line taps (for example, on page 53 of this pdf document). No doubt, these features were included to provide backward compatibility with older equipment. And the result is backward compatibility with older bugs.

California Secretary of State Debra Bowen's decision on the fate of her state's voting technology was announced just before midnight last Friday. The certifications of all three reviewed systems (Diebold, Hart, and Sequoia) were revoked and then re-issued subject to a range of conditions intended to make it harder to exploit some of the problems we found in the security review (see previous entry in this blog). The certification of a fourth system, ES&S, was revoked completely because the vendor failed to submit source code in time to be reviewed.

Whether the new conditions are a sufficient security stopgap and whether the problems with these systems can be properly fixed in the long term will be debated in the technical and elections communities in the weeks and months to come. How to build secure systems out of insecure components is a tough problem in general, but of huge practical importance here, since we can't exactly stop holding elections until the technology is ready.

But that's not what this post is about.

The traditional role of the vendors in cases like this, where critical products are found to be embarrassingly or fatally insecure, is to shoot the messengers. The reaction is familiar to most anyone who has ever found a security flaw and tried to do the right thing by reporting it rather than exploiting it: denials, excuses, and threats.

Occasionally, though, a company will try to look "responsible" by employing a different strategy, acknowledging -- and perhaps even actually correcting -- the underlying problems. This should be understood as nothing more than a transparent attempt to pander to customers by wastefully improving the security of otherwise perfectly good products. These naive organizations -- a tipoff is that they're often run by engineers rather than experienced business people -- do enormous damage by shirking their public relations duty to the community as a whole. Fortunately, this kind of unsophistication is rare enough not to have been much of an issue in the past, although in some circles, it is becoming worrisomely commonplace.

To help vendors focus on their obligations here, Jutta Degener and I present Security Problem Excuse Bingo. Usual bingo rules apply, with vendor press releases, news interviews, and legal notices used as source material. Cards can be generated and downloaded from

Because we follow all industry standard practices, you can rest assured that there are no bugs in this software. We take security very seriously.

Readers of this blog may recall that for the last two months I've been part of a security review of the electronic voting systems used in California. Researchers from around the country (42 of us in all) worked in teams that examined source code and documents and performed "red team" penetration tests of election systems made by Diebold Election Systems, Hart InterCivic and Sequoia Voting Systems.

The red team reports were released by the California Secretary of State last week, and have been the subject of much attention in the nationwide press (and much criticism from the voting machine vendors in whose systems vulnerabilities were found). But there was more to the study than the red team exercises.

Today the three reports from the source code analysis teams were released. Because I was participating in that part of the study, I'd been unable to comment on the review before today. (Actually, there's still more to come. The documentation reviews haven't been released yet, for some reason.) Our reports can now be downloaded from .

I led the group that reviewed the Sequoia system's code (that report is here [pdf link]).

The California study was, as far as I know, the most comprehensive independent security evaluation of electronic voting technologies ever conducted, covering products from three major vendors and investigating not only the voting machines themselves, but also the back-end systems that create ballots and tally votes. I believe our reports now constitute the most detailed published information available about how these systems work and the specific risks entailed by their use in elections.

My hats off to principal investigators Matt Bishop (of UC Davis) and David Wagner (of UC Berkeley) for their tireless skill in putting together and managing this complex, difficult -- and I think terribly important -- project.

By law, California Secretary of State Debra Bowen must decide by tomorrow (August 3rd, 2007) whether the reviewed systems will continue to be certified for use throughout the state in next year's elections, and, if so, whether to require special security procedures where they are deployed.

We found significant, deeply-rooted security weaknesses in all three vendors' software. Our newly-released source code analyses address many of the supposed shortcomings of the red team studies, which have been (quite unfairly, I think) criticized as being "unrealistic". It should now be clear that the red teams were successful not because they somehow "cheated," but rather because the built-in security mechanisms they were up against simply don't work properly. Reliably protecting these systems under operational conditions will likely be very hard.

The problems we found in the code were far more pervasive, and much more easily exploitable, than I had ever imagined they would be.

Eric Cronin found this cute little junior phone bugging kit on sale at Toys 'R Us. Recommended for ages 10-14 (presumably because children any older than that are more likely to be prosecuted under 18 USC 2511 and 18 USC 2512), the kit is basically a tunable low-power FM radio transmitter designed to connect to an analog telephone line. I especially like the way the instruction sheet [pdf] prominently warns of the dangers of eating solder, but only casually mentions the illegality of listening to other people's phone calls once you've got the thing built. (A non-trivial concern, especially considering the trouble that Ramsey Electronics got into with the US Customs service a few years back for selling similar kits.)

As strongly as I feel about the evils of illegal wiretapping, I must admit to having decidedly mixed feelings here. No, kids, don't tap your neighbor's phone. But unraveling the once-forbidden mysteries of telephone electronics has a way of pulling a young geek into a lifetime of technological exploration. It certainly did for me.

I was at a conference recently where everyone was asked to recall their first moment of thinking "I rule!" over some technology. It's a surprisingly revealing question; experience the exhilaration of hacker empowerment at a sufficiently impressionable age and you're hooked forever. A disproportionately large fraction of the answers seemed to involve telephony. (Mine was when I discovered you could dial a phone by flashing the hookswitch. I think I was too young to have anyone to call, though).

So I suppose if the nerdy kid next door figures out how to hook one of these kits up to my phone, I won't be too upset. Just make sure not to eat the solder.

Vassilis Prevelakis and Diomidis Spinellis just published (in the July '07 IEEE Spectrum) a terrific technical analysis [link] of the recent Greek cellular eavesdropping scandal. In 2005, it was discovered that over a hundred Athens cellphones, mostly belonging to politicians (ranging from the mayor to the prime minister), were being illegally wiretapped. The culprit hasn't been found, but there's plenty of fodder for speculation, including mysteriously missing records, suspicious suicide, and, as Prevelakis and Spinellis point out, an intriguing technological mystery.

This would all be interesting enough for its stranger-than-spy-fiction elements alone, but what makes the story essential reading here is how definitively it illustrates something that many of us in the security and privacy community have been warning about for years: so-called "lawful interception" interfaces built in to network infrastructure become inviting targets for abuse. (See, for example, this point made in 1998 [pdf] and in 2006 [pdf]). And, as this case shows, those targets can be rich indeed.

For some reason, wiretapping interfaces don't seem to get much technical scrutiny, and we're starting to see how easy it can be to exploit them to nefarious ends. Vulnerabilities here can cut both ways, too, sometimes making it easier for real criminals to evade legal surveillance. A couple of years ago, Micah Sherr, Eric Cronin, Sandy Clark and I discovered basic weaknesses in the interception technologies used for decades to tap wireline telephones. Many of the vulnerabilities have found their way, in the name of "backward compatibility", into the latest eavesdropping standards, now implemented just about everywhere. Maybe even in Greek cellular networks.

Addendum: I just noticed that Steve Bellovin has a blog post on the same subject here, with some interesting comments and links.

Several people asked me for a list of references from my talk on "Safecracking, Secrecy and Science" Sunday morning in Sebastopol, and I promised a blog entry with pointers. (If you were there, thanks for coming; it was fun. For everyone else, I gave a talk on the relationship between progress and secrecy in security, as illustrated by the evolution of locks and safes over the last 200 years.)

Unfortunately, few of the historical references I cited are on the web (or even in print), but a bit of library work is repaid with striking parallels between the security arms races of the physical and virtual worlds.