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2008 Underhanded C Contest Officially Open
Xcott Craver writes "The 2008 Underhanded C Contest has just opened. Every year, contestants are asked to write a simple, innocent, readable C program that appears to perform an innocent task — but implements some non-obvious evil behavior. This year's challenge: redact blocks from an image, but do it so that the excised pixels can somehow be retrieved. We also have listed the winners of last year's contest, which was to write a simple encryption utility that mysteriously and undetectably fails between 1 percent and 0.1 percent of the time. The winning entry is truly impressive."
We discussed the first of these contests in 2005.
The Microsoft Windows Operating System, pick your version.
This is actually a feature in 'word'...
MP3 Search Engine
(sorry, couldn't resist, I know they've suffered enough already)
Interactive Visual Medical Dictionary
No, the point is to make a utility that appears to innocently redact part of an image, when in fact the information is retrievable. It's meant to be a malicious utility that people would use without knowing that the 'hacker' could recover their full images.
Something like Photoshop's Swirl filter.
Ever seen scans from a FOIA request? They redact certain information regarding sources and methods (and some would claim whatever they feel like at the time). *That* would be a "use" of this technology.
"Enter the registration key" type schemes are more easily accomplished without it being underhanded in nature.
Integrate Keynote and LaTeX
I'm sure it would be nearly impossible to hide the evil code here, because anything that isn't a simple assignment loop is suspicious.
Maybe stick in stuff in the image loader, image temporary copy code, and keep the blackener to the obvious implementation, then stick stuff in the saver.
I thought some crazy stuff involving function pointers as the function to call to return a black pixel might be promising. Maybe use some out of bounds array math to change one function pointer to point to some other code.
More precisely:
The point is to make a utility that - when viewing the source code - appears to innocently...
It is no challenge to make a closed source utility which does something evil even though it appears to do something innocent. Most viruses do that.
The challenge is to hide the the evil behaviour in simple and open source code.
Wouldn't it be nice if the original under the blacked out area could be compressed and then put somewhere else in the image.
It would be much easier if one could just use an algorithm which just displaces the pixels and then forget to randomize the displacement. This could look much more innocent than the above.
That black area has so little expected channel capacity that hiding anything in it is kinda difficult.
Unfortunately the code for the blacking out can be made so small that it is tough to hide anything in it, unless ppm offers some ways to add complexity in some innocent way.
I wonder what means of deciphering the hidden area are allowed, i.e. can I write another program to get the kitty face information back?
That is a really cute picture. I wonder what it is thinking.
Je me souviens.
because the way it dumpes the key into the output is hidden in such a underhanded, innocent way...
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Reminds me of a "compression program" back in the early 90's. Seemed to compress better than Zip or RAR and was pretty fast too. You could also test it by compressing and uncompressing a few files, and you got your original back.
Turns out it just copied the contents to a temporary file and "uncompressing" got them back from there, while the "archive" was just random junk. Better yet, the temporary file was just a circular buffer, so when it filled, old data got discarded.
A polar bear is a cartesian bear after a coordinate transform.
Now we can speculate what the authors intentions behind the contest are.
I think their FAQ addresses most points pretty well:
http://underhanded.xcott.com/?page_id=7
I hope sensitizes open source programmers programmers to take great care with peoples submissions to their projects. Only good can come from that.
Je me souviens.
The PNG specification allows for private (nonstandard) data chunks that can be flagged to be preserved by any program that doesn't understand them. That would seem to be the most straightforward way to hide redacted pixels in a recoverable way, at least if the input file is PNG.
You mean like the FBI in PDF's?
...a job, giving them full expression for their nefarious skills, at a well known software company in a north-western US state, where they can join a massive team of (unconsciously) underhanded coders.
-- In the beginning was the WORD, and the WORD was UNSIGNED, and the main(){} was without form and void...
Nearly every piece of C code that I've ever seen has contained some hidden malicious (or at least willfully stupid) behavior.
Wavelet Intelligent Compressor. And it was intellingent, indeed. It had a compression scheme so good it could compress its own .wic files down from megs to bytes.
But what do you mean with "random junk", do you mean my .wic based backups could be in trouble????
Hosting 20G hd, 1Tb bw! ssh $7.95
Arrays, pointers and functions, no memory protection, dangerous strings. I would like to see the same contest with other 'safer' languages, say Java or Python.
What languages are best suited to underhanded tactics, that is, seemingly innocent but evil?. Notice that underhandedness is very different from plain old abuse -- anybody can write unreadable programs in their favorite language. But, can you make them "clearly read" something different from what is actually written?
Seems like an important question for people who use Open Source because of the difficulty for adding back doors. For many applications, security is at least as important as speed, and you already have The Shootout for that.
So it could be sufficient to replace the image with something that the inspector doesn't _want_ to look at. Sort of like a "somebody else's problem" solution. Your code would pass inspection because it would appear to have overlaid the original part of the image with the hardcoded image stored in code (the unsightly image), but there would be a bug which only copies every second pixel or something. Anyone looking at the redacted image wouldn't notice that the original data is still visible simply because they would have to look at the unsightly image too closely. They'd just rubber stamp the solution and say it passed, and then go and lie down for a bit.
Alternatively, you could go the opposite way instead and use an image which would distract the attention of the inspector enough that they wouldn't notice. Something with breasts would probably do it.
Can I have my $100 gift certificate now?
Easy, just write it in whitespace, and present the source in paperback format.
OK, it is generally believed that OSS is inherently secure because so many eyeballs can examine and vet it. But as this contest shows, it is possible to include backdoor behavior "in the source for everyone to see" without it being discovered. Oh, and note to self, don't download any open source image editing software in the future ...
The more you regulate a company, the worse its products become.
firefox 2?
courtesy of crazy Japanese censorship laws. Google for gmask or see examples at Lecture on masking (Yes, it's SFW)
Some people have had some rather disappointing experiences with that one.
There seems to be an error in the supplied ppm.c library file:
p.rgb[i] = z.pixel[y][(x+i)*3*z.bpp];
This only ever gets the R component, as all offsets are multiples of 3. I think the right code is:
p.rgb[i] = z.pixel[y][(x*3+i)*z.bpp];
Maybe this is part of the assignment :-).
Seemingly innocent code...that mysteriously and undetectably fails up to 1% of the time. What's the big deal? This sounds like any given day at work for me.
Taking a look at the 2006 entry reminds me of a program I used to have to work on:
Essentially it was a giant checkbook for a city government organization for some sort of subsidized housing program. There were two numbers to be calculated along with a grand total (primary and interest maybe. I forget now) The code took about 10 minutes to execute and looked something like this... and yes this was unfortunately in Visual Basic
Label1.Caption = Function1
Label2.Caption = Function2
GrandTotal.Caption = Function1 + Function2
Some of the functions themselves were already bloated to begin with. That ontop of calling both of them twice was just kinda nasty though.
Pancakes. Oh I blew it.
How about this:
declare places_to_block(constant)(array)(global)
Function (copy places_to_block to a temporary buffer to "find the size")
Function (screw up the garbage collection by using the wrong error catch)
Function (abuse printf to copy the wrong number of bits to collect for entropy
Function (Block_Places(places_to_block))(use entropy to copy "random" noise over the places to block))
If video games influenced behavior the Pac Man generation would be eating pills and running away from their problems.
And I have a voodoo doll with your name on it. Coincidence?
Caesar si viveret, ad remum dareris.
This cheers me up just a little.
We rage against the management decisions of MS, but I'm positive the ranks are filled with decent guys just trying to pay for dinner & rent.
"We haven't a clue what this does but it's vital..."
Seems to me that if the source were opened, within 5 years we'd at least know what all the hacks did, even if they were still necessary.
My first Journal Entry ever, in 8 years! http://slashdot.org/journal/365947/aphelion-scifi-fantasy-horror-poetry-webzine
I'm looking at the Runner up entries in the the 2007 contest. In these they use an "Xor" Swap trick, which is a way of swapping two bytes in place without having to create a temporary storage element:
#define SWAP(x,y) do { x^=y; y^=x; x^=y; } while (0)
The terse explnantion says this some how poisons the RC4 encryption.
I don't get it. Is the Swap doing something else besides swapping? when does it fail? I'm not getting it
Some drink at the fountain of knowledge. Others just gargle.
Is that an idea?
Make a routine that appears to copy the values (for retrieval by your own code) but accidentally/nastily hides information in the process of copying?
My first Journal Entry ever, in 8 years! http://slashdot.org/journal/365947/aphelion-scifi-fantasy-horror-poetry-webzine
How about a timestamp encoding that forgets that 2008 is a leap year?
My first Journal Entry ever, in 8 years! http://slashdot.org/journal/365947/aphelion-scifi-fantasy-horror-poetry-webzine
Pfft. I don't see what the big deal is. Just about every app I've ever written does this.
I read Usenet for the articles.
Using XOR was my first thought, as well. As you say, it's relatively well-known that XOR is reversible. What is less well-known, or more plausibly deniable, is a convoluted logical expression that evaluates the same as an XOR, but it composed of more primitive operators: Exclusive disjunction - Equivalencies, elimination, and introduction, to wit:
NOTE: I'm using:
- "+" to denote "inclusive or"
- "*" to denote "and"
- "^" to denote "not"
p XOR qAt this point, you could use a simple nested conditional, or, even better, a nested conditional assignment statement, ala:
For bonus points, wrap the preceding inside a function or macro definition.
"There are two ways of constructing a software design; one way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult." -- C. A. R. Hoare
(NOTE: I'm a little rusty on my C, so please ignore syntax errors.)
... or the version of Acrobat they sell to the federal government.
I think the most important thing is that, according to the FAQ, it doesn't have to be black, although I'm pretty sure someone will get bonus points for figuring out a way to hide something in a black overlayed rectangle.
Hate to be pedantic, but I think the word you're looking for is "steganography"
stenography == the action of taking dictation
-- it's ridiculous how many people misspell ridiculous... (damn, damn, damn...)
Their definition of "blacked out" for the 2008 contest allows colored rectangles or "random noise" replacing the part of the image to be blacked out. The latter would allow doing something like a crypting of the chunk of the image (in the guise of creating random pixels, of course). In that case, everything could be fully restored; no need to just hide things steganographically in a few low bits of black or anything.
(Of course, the challenge of making the program appear to be doing something else is a key part of the work.)
Love many, trust a few, do harm to none.
Could someone provide a link please?