Interview with Patrice Godefroid

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En provenance du cours de University of Maryland, College Park

Software Security

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University of Maryland, College Park

Software Security

651 notes

Cours 2 sur 5 dans Specialization Cybersecurity

This course we will explore the foundations of software security. We will consider important software vulnerabilities and attacks that exploit them -- such as buffer overflows, SQL injection, and session hijacking -- and we will consider defenses that prevent or mitigate these attacks, including advanced testing and program analysis techniques. Importantly, we take a "build security in" mentality, considering techniques at each phase of the development cycle that can be used to strengthen the security of software systems. Successful learners in this course typically have completed sophomore/junior-level undergraduate work in a technical field, have some familiarity with programming, ideally in C/C++ and one other "managed" program language (like ML or Java), and have prior exposure to algorithms. Students not familiar with these languages but with others can improve their skills through online web tutorials.

À partir de la leçon

PEN TESTING

Penetration and Fuzz Testing

Penetration Testing: Introduction10:11

Pen Testing14:28

Interview with Eric Eames31:46

Interview with Patrice Godefroid35:06

Rencontrer les enseignants

Michael Hicks
Professor
Department of Computer Science

[SOUND] Okay, so today I'm really happy to have with

me Patrice Godefroid a Principal Researcher at Microsoft.

I'm going to now read a little bit about him.

His bio.

So he's been at Microsoft in Redmond since 2006 and

before that he spent 12 years as a researcher at Bell Labs.

There he earned his Bachelor's and Doctorate, sorry not there.

Before that he earned his Bachelor's and

Doctorate degrees from the University of Liège in Belgium.

Patrice is well known for having invented VeriSoft.

Which is the first software model checker for

mainstream programming languages like C and C++.

And more recently and,

and something that's going to be a big topic of today's conversation.

He codeveloped SAGE, which is the first whitebox fuzzer for security testing.

And SAGE has been credited with having found roughly one-third of all of

the security vulnerabilities discovered by file fuzzers.

During the development of Microsoft Windows 7.

So, Patrice, thanks so much for joining me and welcome.

>> Well thank you very much for having me.

>> All right so I'll get right to it.

So in this class the class that I'm teaching on

Coursera we're covering common security problems in software.

Like buffer overflows and SQL injections and format string attacks and

things like that.

And you've worked on automated means for finding and preventing these problems.

So I'm curious given all of your experience,

what's your view on the state of the art?

What are these tools do well, and what are they not so good at.

>> Well I think yes, so so

over the last 15 years there has been a lot of progress on these kind of tools.

So automatic program analysis tool.

There, there, I would say two main classes and I hope you would agree with that.

The first class is static program analysis.

The second is dynamic program analysis.

So static program analysis tools.

They can read code.

Usually source code.

[SOUND] And then they scan it, and

they kind of try to find all kind of issues with the code, like bugs.

Like those that you just mentioned.

And then dynamic program analysis tools, they run the code.

So usually the, the, one execution of the code and

then do all kind of check during the execution.

Again, to try to find all kind of like [INAUDIBLE] or bugs.

And so, and then you can run them repeatedly and so

you can check multiple execution this way.

And I think that really, like for instance, for

static program analysis, I mean it really took off.

I think I would say around like 2000.

There's starting to be really commercially available tools.

Inside Microsoft we had, we have a a tool like that called Prefix.

That started to be developed within the late 90s, 90s and early 2000s and

was deployed really on a large scale thoughout the company.

And these tools we found really lots of issues and help and

help quite a bit and, they and they are use, used routinely today.

And I make also tools that have been used for

quite a while so right time checkers lets say.

Like [INAUDIBLE] fire, internally we have a tool called True Scan.

So these tools also find a lot of bugs and memory leaks and performance issues and

things like that.

And then in the area of security also starting in the,

your early 2000 I would say around that time.

There have been also or a lot of work on security testing also called fuzzing,

basically to try to find security unreliabilities.

Mostly in parsers for files and packets.

And then there have been also a lot of progress over the years

in having more sophisticated techniques finding mobile bugs using fuzzing.

So, I mean that's kind of a general [LAUGH] answer.

So there's been a lot of progress, but there's still room for improvement.

>> Uh-huh. Do you, do you at this point as you

say they, they've been under development of maybe 15 years.

Are there things that these tools are just awesome at.

You've mentioned they're in routine use.

>> Yeah. >> For what things do people routinely use

them versus things that are maybe still somewhere off in the future?

>> Right.

So so I know a little bit better the, the area for like systems code safety.

So actually.

For like cross site scripting attacks, and and like SQL injection bugs,

things like that.

So I do not know what the ratio of static versus dynamic analysis.

But for buffer overflow, memory, corruption, bugs, etc,

both are used extensively.

So usually static analysis is used first, earlier, as the code is being written.

And now you buy into these tools that are basically embedded into, I mean,

the broken environment like Visual Studio.

And as, as soon as you type, it can also perhaps flag some errors.

And so they are used early on.

And so this static are, these tools usually they are fast.

And then they can be increase size.

And so, and,

in contrast the dynamic analysis tools are used when you can run the code.

So after you can compile it, [INAUDIBLE] builds.

And so they are run later.

And they tend to be more precise, but they only check some execution.

Typically not all execution of the program.

So they're, they are very much complimentary.

And in practice, they are used at different points during the development,

software development.

And so they are very much complimentary.

And, we're still, I mean, as a community or inside Microsoft.

So developing, developing these tools further to

improve basically this precision.

And type of bugs that we can find, and reduce the cost of using these tools.

>> Okay, great.

So, so you yourself have worked on these sorts of automated analysis.

Most static analysis.

So software model checking in the case of Verisoft.

Back also since then whitebox fuzzing.

So I'm curious having worked on software model checking for so long.

What prompted the switch to working on whitebox fuzzing starting with

I believe DART which was a forerunner of SAGE.

>> All right.

So, I mean, so, in my mind, VeriSoft, and DART, and

whitebox fuzzing, and implements whitebox fuzzing.

They are all related to this idea of software model checking, where one wants

to try to prove that you have, to exhaustively test programs.

In the case of Verisoft the main source of non determine is

there was due to concurrency so the goal was to find concurrency related bugs.

And in the case of DART or

white box fuzzing the goal was to find bugs in data driven applications.

And so, so there the non determine is due to the large input space for data.

But the goal is the same, in the sense that, in the limits.

So if you, if you're applying to small example, or

if you let it go long enough, you get verification.

So verification means it's a tool.

A verification tool is a tool that can not only find bugs, but

also prove the absence of bugs.

Or a, a class of bugs, under some assumptions.

Or a testing tool is just a tool to find bugs.

And so so myself and

many others in the research community have tried to basically develop new tools.

That are inspired by verification techniques.

In order to define new bug finding techniques, either static or

dynamic, basically, testing-based, super testing kind of techniques.

So the reason for the switch in, in my case is simply because ,.

So when I was, I worked at Bell Labs for 12 years and

their class of very expensive bugs, where inside communication switches.

Like optical switches, or CDMA-based station, or phone switches.

And so there, you had most of these bugs where you do concurrency issue,

reactivity, real time issues inside really the core of a switch.

And these were, like, very expensive box and very hard to find.

And that's why a lot of work initially on model checking in the initial labs,

at least, came out of the labs.

Because there was a lot of interest,

a strong interest in these type of techniques.

Which have been proven to find quite subtle and

expensive bugs physically inside switches.

And when I move to Microsoft in 2006.

Here at Microsoft, I would say that as a class, the,

the most expensive bugs that Microsoft faces are probably security related bugs.

And so there, this, it's not concurrency, really.

It's really bugs that are due to malformed inputs.

So, for instance, Windows client.

So, Windows that runs on every lap, I mean laptops running Windows, for

instance, etc, or PCs.

Includes support for about more than 300 file formats.

So they have 300 file parsers that are embedded in every

laptop running windows for instance.

And so there's, it's a big attack circus.

In the sense, if you can craft specific input file and then open it or

process it through the software running on your machine.

And you can trigger buffer overflow.

In principle this could be perhaps be exploited.

And then you could hijack the execution of the process that runs on your machine.

And so this is, so a big problem for Microsoft Office is this second big

target, and big customer that we have for these type of techniques.

Because Office also supports, depending on how you count.

The tens, thousands, maybe a few hundred,

depending on how you, the limits basically.

But parsers and sub-parsers, etc.

And both Windows and

Office are successful products, they have been deployed on over a billion machines.

So we have, when we have security related bugs that are very visible.

We need to patch basically a billion machines through,

like patch Tuesday kind of bugs, etc.

So this is very expensive for Microsoft.

Hence the interests of kind of developing and pushing further techniques or

finding bugs in this type of application.

>> So Microsoft, before you got involved with SAGE was using fuzzing technology.

And you developed this new approach that was inspired by program analysis to

do fuzzing.

I wonder if you can characterize maybe the difference between other sorts of

fuzzers that Microsoft uses and, and SAGE.

And then also maybe the balance of how much time is

spent using SAGE style fuzzing today.

Versus maybe, before you, you know, when you got started.

>> Right.

So, I, I, I, I, I would say that there are three main types of fuzzing.

And and they were they were proposed in that order.

Well the first type of fusing is the simplest one.

It's so called black box fusing.

So it's random testing.

So if you have for let's say five fuzzing you have a five parser.

Parser means here just a, a program I'm going to read that file and

do something with it.

And so, so the, the simplest form of fuzzing, and the oldest one and

the most basic one and the more used one, is called black box fuzzing.

So you take, for instance, a, a well-formed input file in that format.

And then you randomly fuzz, you randomly switch the value of bits in that file.

As with that base variance, like a by, by, by causing where you to run by two,

256 values, and then move to the next one, etc.

So you can do the fuzzing.

This way, you generate a lot of variance.

And then you o, you try to open this file, run the program that reads that file.

With all these variants, it takes a lot of machine time.

And you hope to find a bug this way, like a bug overthrow, for instance.

So that's blackbox fuzzing.

The second class of fuzzing techniques we call them

grammar based fuzzing techniques.

So there, in addition, you have a grammar that

represents the input format of the the, the, the, the, the inputs.

That's the, the format that the application that your interested in to

fuzz is supposed to take as input.

So for instance you have, like Excel, or Word, or JPEG or GIF or whatever.

And so, so now you have a grammar that's basically constrained the, the fuzzing a,

a bit more.

So you can say well, you, you, you can go through prediction rule of the grammar.

And by construction generate basically inputs that are accepted in

the language of the grammar.

And then you can also enhance grammar base fuzzing this way by having heuristics.

For instance saying well these four bytes, they're really meant to be an integer.

And then you can.

So, to, and try more often like values with many like 0 minus one.

And even associate probabilistic weight through the production rule of

the grammar.

So basically that,

when you go traverse and generate inputs so you can control the.

Is if we randomly fuzzing this way.

It's a way to guide random fuzzing.

And, and make it much more intelligent by science based grammar.

So and this is also a very popular approach and the, the,

the drawback of grammar base fuzzing is that you need a grammar.

And so the grammar-based fuzzing,

in some sense, is as good as your grammar, to a large extent.

And so this has been also used quite a bit, including inside Microsoft.

And the third kind of technique large class of techniques is what I

would call whitebox fuzzing.

Which is what we,

we started really developing and, here at Microsoft 2006, roughly speaking.

And so there, in whitebox fuzzing.

We, we, we run the program so we have a, a file parser, and,

and, and a C file as an input.

And then we run the program on that input to see what it does with it.

And we do what's called simulated execution.

When the program is running,

we also execute that specific execution symbolically.

And we, we, in this, basically the outcome of that is to generate,

to see what the program does with its inputs.

So we generate constraints that correspond to tests on the inputs.

And then this, and then later on we can negate these constraints to try to, and

use the constraints over to generate new tests.

That are going to drive the execution of the program through different code path.

And so we call these whitebox fuzzing because there the fuzzing is

not done offline.

But really we have to analyze the program and see how what it does with it's input.

And then the tools suggest different inputs to drive a param through

different code path.

That's whitebox fuzzing there's various [INAUDIBLE] that have been proposed in

various level of past precision.

The advantage.

So, whitebox fuzzing is more complex, the tools are more complex.

But it's still fully automatic.

So you don't need a grammar.

And so, once you have a tool like that, it's,

you press a button, and it, essentially goes, basically.

So so it's still a victory.

I think blackbox fuzzing was the first and

probably started to begin to be used quite a bit in the early 2000.

Grammar based was, I think,

soon came after, like also between 2000, 2005, started to be developed.

I mean, I'm talking about main stream kind of fuzzing cycles.

And then we started with 2006 etc, whitebox fuzzing.

It took us a few years to get traction, and, and get, deployed on a large scale.

And today we, we still, actually Microsoft we use still,

use the three type of fuzzing techniques in production.

With the exception for grammar based fuzzing.

because sometimes we don't have good grammar's for some formats with so

many different formats.

It's finding the format itself is a hard problem.

Their has been attempt to try to automatically generate these grammars and

reversing hearing.

And sometimes in whitebox manner, but these are mostly I think a,

a stayed in research cycles so far.

I mean it's less frequently used.

And so grammer based fuzzing there are people exchanging grammars on

the internet etc.

So for some formats they are very well covered and [INAUDIBLE] covered.

And it's labor intensive.

I mean you need to pay somebody who's going to write for

weeks basically grammars, and guess and try.

So this is kind of more expensive than blackbox fuzzing and

whitebox fuzzing in some sense.

The increment passes higher.

But today we use all three inside Microsoft usually.

>> So there are all, and so

I take from that that they all are effective in various ways.

That for example, I could imagine that in whitebox fuzzing, you're going to follow.

You're driven by the control paths of the program and

some control flow paths are just, they are just harder or difficult to reach.

Whereas you might get very lucky when you are doing a blackbox thing or

you are not so lucky.

Because you put the extra effort in to writing the grammer.

You're able to get sort of deeper into where the program goes.

Or, or maybe deeper is the wrong word.

You just end up covering different parts of the states base of the program with

these different techniques and so they, they complement each other.

>> Yes, I, I, I think your, your intuition is absolutely correct.

I mean this is intuition at the end because it's still, we're still trying to

figure out what's the really fine print of what is, what technique is good at.

And where there are threshold, what kinds of bugs, etc.

But yes, in the end I think they are still very much complementary.

I would love to be able to claim that SAGE finds basically everything that

other fuzzers have, can find.

And, in some cases of it we've done some experiments, etc.

But in general also the product teams they don't want to

put all their eggs in the same basket, and so they going to.

Also, if a, a, a, a hacker is going to use a blackbox fuzzer, you want to,

you want to also use blackbox fuzzer.

Because that's what they would find, basically.

And in practice, also.

So when we run fuzzing, like in large organization like Windows.

We don't run, fuzzers don't run exactly on the same code, as well.

Which make comparison difficult.

So, for instance, you ca, you might, first, as a small, first kind of test,

ran some like, default like, like for instance blackbox fuzzing.

And because it's offline fuzzing, it's easier, you can,

it's easier to kind of test it on like, unstable build, and things like that.

And later on you can go to the more sophisticated tool that needs to

run perhaps for a longer period of time, or, or, and things like that.

So it's, it's very much a mixture in, in the end.

But yes, and, and so, absolutely programmer-based fuzzing for

instance, especially for like very sophisticated languages.

I mean, you cou, it, it,

having a grammar, good grammar give you a heck of a head start.

Basically to understand what the format is about and

how to drive the execution of a program.

So in fuzzing, in general, we always use seed files, so

well-formed inputs that give us also a head start, right?

So you can also have a combination, where you use grammer based fuzzer.

You generate the 1,000 seeds, cover the grammar well.

And then you use that as this suite basically for whitebox fuzzing.

So, we use, we use this kind of techniques as well.

I mean, using seed files is also a common practice in the fuzzing world, but

we also use this whitebox fuzzing.

And so, we also to refresh the seeds, or, and

how to kind of, try to have more diversity in suite.

Also, and their grammer based fuzzing can be useful for that.

So. >> I'm wondering as as you talk about

the different tools.

And the history that Microsoft has had with using these different tools.

And also the history of automated analysis.

Having started with with Prefix, maybe in the late 90s.

And it become into more common use.

sort of what the story was.

From your point of view you're, you're, you come into the research division of

Microsoft and you just start to develop this technology.

And then you you know, what was the step that went from a tool,

a prototype that you were developing.

To getting to the point that now it's being run on, you know, like you said,

Office and Microsoft products that are used all over the world.

>> Right. >> I imagine that that story of,

of getting it adopted is going to mirror at least a little bit of story.

That maybe people taking the class that they try to get tools used at

their companies.

You know, maybe, what they're certain road blocks or what-not that you encounter,

that maybe they would encounter as well?

>> Yes, so.

We started the development of SAGE, which tool that can implement this

whitebox fuzzing approach and we, and in 2006.

In 2007 we had our first prototype.

And we were fortunate to have some people in

the current group that were really intrigued and interested in this.

But at the beginning we didn't know how successful it would be.

And so we started basically applying it to a handful of.

And we found bugs.

Bugs that have been there for a long time, and

that were missed by everything that was throwed at them so far.

So, so that's kind of whats and then we had there was the, the managers.

The person or the head of security testing for Windows Client for

Windows 7, who, and his name is Eric Douglass.

And he, he was actually an early,

he kind of was early on suggesting that, encouraging us to do this project.

And at some point he decided to one day, so

he was at the head of fuzzing, white fuzzing.

Fuzzing actually for Windows 7.

And then he decided to invest basically more significantly in SAGE,

and then it was deployed for the first time.

And about two-third of the, the, the file parsers embedded in Windows Client

were fuzzed for the first time with SAGE in the 2008, 2009 time frame.

And it turns out that it's, wasn't, it's a very effective way of finding bugs,

especially in binary parsers.

And so, as, as you mentioned earlier.

I mean, at the end to give you an idea.

SAGE was credited to it found about a third of all the file fuzzing bugs found

during Windows 7.

And so because SAGE was also the first.

I mean, U2 at the time was run last.

Which means that all the bugs found by SAGE were missed by

literally everything else.

Which is blackbox fuzzing, grammar based fuzzing when it was applicable.

And also static program analysis that was run way earlier.

But and maybe, I mean,

by missed I mean that maybe the static analysis tool would have flagged that bug.

But among a sea of false alarms.

And I do not know exactly why, but in the end it was, the bug was still there when

we, we, we paused it so when we run these tests basically.

When they ran, the Windows team ran these tests.

And so the, Windows 7, that was our first basically big customer.

We were also lucky that in, and this is also something that I,

I recommend in some sense for other companies, and this is a trend.

Very visible and inside Microsoft.

There has been a trend of centralizing fuzzing.

So in Windows Vista for instance, which was the back, before Windows 7,

the Windows team, they was doing fuzzing in a distributed manner.

So every, and maybe, let's say, I'm just making this up, but

let's say 100 group that need to do some fuzzing.

Well there would be 100 fuzzing guy, and

they have to grab some machine and do some [INAUDIBLE] some fuzzing.

Starting in Windows 7 Client, they decided to centralize fuzzing.

But for me, the true provider was great because I

would just need to talk to that specific team, and I go leveraged this way.

So, there, the, the, if you, if you like the head of the development team, and

I'm the the fuzzing group.

What we have to do is to, we identify, you have to identify, basically,

that's part of the process that we use at Microsoft.

There has to be a,

an architectural, sorry, a review at the architectural level for your component.

Where you have to identify your untrusted interfaces.

And then you have to give me some kind of test driver and some seed inputs.

And, but I need, the centralized fuzzing lab will run the test.

Will run all kind of fuzzers, do all kind of things, triage the bugs.

Eliminate duplicates, and then I will send you email, I mean we'll use.

But rep, database kind of thing to communicate, and then I'll,

I'll, I'll, I'll send the bugs back to you, basically.

And so now you, for

you, you don't have to worry about all this fuzzing business, etc.

A bunch of experts are doing it for the entire Windows organization.

And so at the beginning it was Windows 7.

But now it moved, Windows 8 moved to the uncentralized fuzzing.

Now we have recently a reorganization where its operating system growth,

including Windows Phone and XBox, and a single, centralized team.

And the same trend happened in the Office.

And so for two provider it's great because now I have a few but very smart users.

And so for sophisticated tools I get it's easier for

me to really get a few people then hundreds.

Actually do not do that don't have the bandwidth, the time to do that.

And then it allows basically more sophisticated analysis to be run as well.

because they have a lot of machines available, for all kind of fuzzing but

also for basically available.

>> That's really interesting to hear.

So that, kind of dovetails into another thing I'm curious about,

which is so you described an evolution of the development process.

Where people are using static analysis all the time.

Of course they're doing unit testing and code reviews and

things like they, they've always done before.

And then they also now are adding this very late phase, right?

I mean this is to the point where these things are building running.

And you can hand them off to a third party to do this fuzz testing with them.

I wonder, you know, stepping back and looking five or, or

ten years into the future.

Seeing how the development process has evolved to the current state.

Where, where do you think things are going?

Where, what potential is there that's in development that's yet to be exploited?

How are things going to get better?

Are certain practices going to fall away?

Can you look into your crystal ball and

imagine what thing will look like in five years.

>> Yeah this is a tough question.

As a Yogi Berra used to say,

it's hard to make predictions especially about the future.

>> [LAUGH] >> But so I, so

I, I, I don't know, but one trend that one sees and

not just here but externally, I mean, and the market as well.

Is perhaps having like like program analysis of

ffuzzing services where you have basically ,.

So you can kind of as an individual like company you might

outsource a little bit of these analysis techniques.

And perhaps, I mean, you still need the expert for the, the.

But, but, for

the techniques the tools themselves would be running in like a cloud for instance.

And so, now, you get the economies of scale, this way, or

you can mind, basically.

I mean, how you can do more sophisticated analysis, for instance, and

find APA, API usage bugs.

Or I mean, cross-application kind of bugs, and all kinds of things like that.

So this is definitely a training going on.

And maybe in testing it will also reach that point.

It's little bit cross-structured, a bit more complicated.

If you do for

instance Windows, which some of the stuff is really close to the hardware.

So it's hard to, you cannot run this on a standard VM etc.

But for higher level application I mean definitely it opens up new opportunities.

Economies of cost and

also perhaps sometimes running more expensive than ISIS.

another, general research comment I mean comment about research or.

They could do also, hopefully we will continue to see new tools.

And especially perhaps combining, trying to combine the strength and, and, and,

of both static and dynamic analysis.

By static, the strength of static analysis is fast and

can go anywhere, kind of things, and, and, and always on the kind of, tools.

And in dynamic being precise, very few false alarms.

And so that's the strengths of dynamic programs is and

have more and more of and package them in a way that is really usable.

By ever first basic application domain, or hopefully, for large classes of users.

So, these kind of tools becomes more and more main stream.

Overall, I think there is still a lot software being written.

And of course its more than ever impacting society.

Security is very critical to many different type of.

So, there will be more progress.

It's hard to crisply define exactly how progress will happen,

but I mean there is a need, so it should happen.

>> I, I just thinking about this synergy that you're talking about

a static versus dynamic analysis.

I'm wondering whether just thinking about the way things have evolved at

Microsoft that.

So one point of view might be that there are these very simple complete.

You know, very likely to be correct low false alarm static analyses.

That can find bugs really fast while you're developing your module.

And this is good, because you can't run the code yet.

It's not part of a complete application.

And they find these bugs, and

they, therefore these bugs get eliminated maybe early on.

So I imagine this is sort of what's happening now.

But then there are more sophisticated static analyses,

you were mentioning verification before.

That you might be able to prove that your, your component sort of does the right

thing for some specification of, of the right thing.

And then I imagine that that will have impact on downstream use of tools, right?

So when you're, the, the more components you develop, say,

in type safe languages or using static analysis upfront.

That creates an opportunity for the tools later on.

Rather than treating, you know, every binary as the same.

If this binary came from.

Become a, a fuzzing.

Even whitebox fuzzing might be a little bit different.

So, I, I think, as you say, it's hard to look and

see how these, this interplay will, will evolve over time.

But seems to me that there's an interesting opportunity there.

>> Absolutely.

And, eh, and there is a whole class of bugs.

I mean, most, I mean a lot of development currently going on in developing apps, for

instance, for like smart phones and things like that.

Or they are like, browser and or application.

And fortunately, this is not really my area of expertise.

But this is also, the world these are like sub-worlds, so to speak.

And and it's, I mean, this sense,

I'm, I'm, the comments that I made, I think, are, are applicable to all of them.

But maybe I was thinking more of a systems call, systems code,

and a buffer overflow kind of things.

And like, networking software and, and like file parsers, and things like that.

And so also absolutely, I mean,

in the order, like an application development for like yeah, apps.

Or like phones, for instance, etc, or for like the web and

so these are also other very specific kind of markets, so to speak.

And so there's, there's also a lot of new tools coming up and

different approaches there.

And so definitely the, the world is, is changing.

I mean, if you look at the five year time frame, it changing quickly.

>> That's very cool.

I wonder so just to finish up and continuing to look ahead a little bit,

maybe a little bit nearer term.

Can you say a little bit about research problems that you or

the community working on.

That these sorts of techniques, symbolic execution or,

or whatever, that supports whitebox fuzzing.

What are some of the problems that you're looking to solve today?

>> Right. So, the, the, that's, that's,

there's a lot of work currently being done in SPAs and as you know.

But to solve our two main, I mean, personally the way I view it is or

a simple way to, to, to, to, to see what's going on is twofold.

So in the short term here,

so one, one, one problem is to see how far come verification.

So sometimes we have run SAGE for instance, for a long time now.

So actually we have run SAGE now for

total, roughly speaking to give you an idea about 500 machine-years.

So SAGE has been running nonstop on average about 100 machine

over the last five years.

And, today as far as I know, so it's like the largest computational usage ever for

an SMT solver.

The satisfiability [INAUDIBLE] theory solvers.

And so, but, one thing that's so

in some cases we've been running it for a long time.

And and we don't find bugs anymore.

And so now, how far away from verification.

I mean, how can we even improve the a techniques especially the,

the, the techniques that deal with past explosion.

Explore in such a way to have complete coverage even of two size of inputs etc.

So that's one, so it is,

of course, related to all their approach, related approach to program verification.

Like so-called verification condition generation and

bounded model checking, etc.

Which are other techniques, basically, that try to take programs, and

have a logic, precise logic representation of those programs.

And then you can.

And using Silver reason very effectively,

very efficiently about the possible be, be, behaviors of the program.

So that's one direction is one, how is the gap with the verification.

The other is try to find, I mean, short-term.

More application domains.

So for instance, SAGE is used mostly today, still today for file fuzzing.

But now what about packets?

What about services?

What about unit testing of in general, for instance, what about managed code?

So we have another project called Pack Seer, which, which tells you,

you need testing for .Net code, etc.

But so how can we get more usage and users for that.

And so we try to find basically this machinery of using symbolic execution and

constraints over.

Is still very limited to a specific application domain.

And so while we, we're very happy and proud of that success I

mean this is just the, the tip of an iceberg or scratching the surface.

I mean most developers at Microsoft do not write code for, for five parser.

So how do we reach other, application domains on your other communities.

How can we maximize the impact of this type of research,

not just the work we do at Microsoft, but on a community basis.

How can we impact the world further in order to continue the research,

get our funding, etc.

Of course also.

But, and so there, I mean, so, like, trying to get better at what we do,

which is the verification angle.

And also trying to make what we can do already more applicable to

a larger class of applications and users is another main theme.

>> Okay, fantastic.

Well I, I don't have any more questions.

Unless you'd like to add, I will say thank you so much for joining us.

>> Well, thank you very much for,

for, for having me, and giving me an opportunity to talk about this work.

>> Fantastic, thank you.

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