Date: Sat, 15 Nov 2014 12:17:49 -0800 From: Michal Zalewski <lcamtuf@...edump.cx> To: oss-security <oss-security@...ts.openwall.com> Subject: Re: Re: strings / libbfd crasher > OTOH the "most" part in "most compression utilities" is somewhat > questionable. There are quite a number of them. E.g. File Roller supports > arj, lha, zoo... Sure, I mean, the stuff people normally download and click on without hesitation (tar, gz, zip, xz, 7z). There are hundreds of less common tools and libraries that are probably awful. >> The default operation of >> /usr/bin/strings and the way many people ended up using it arguably >> violates that assumption in a particularly pronounced way. Tools such >> as objdump are a bit of a grey area, too. > > Why is that? I think using objdump to analyze malware is quite common. Oh, I meant that it's still a bit sketchy (maybe less than 'strings' because the untrusted input use case is a lot more specialized and fewer people are at risk). >> [...tcpdump...] > > Not good. Haven't you looked into it -- are these crashes due to malformed > pcap format or due to malformed traffic? Both, IIRC. There are some test cases that come with afl-fuzz. > BTW any crash in imagemagick during image processing is regarded as a > security issue? Probably a grateful target for fuzzing. Well... probably? For example, some sites use ImageMagick to convert / resize user-uploaded images. One would hope that they check file headers and only accept JPEG / GIF / PNG or so, but that's probably not universally true. >> Now, the quality of the *average* OSS project is probably comparable >> to libbfd, but the average OSS project is probably less likely to be >> exposed to untrusted inputs under normal operating conditions. > > Sorry, I don't understand your stance. There is a whole world of desktop > tools and applications -- from `file` and `strings` to LibreOffice and > Blender. And most of them process files received from untrusted sources. I wouldn't describe LibreOffice as a typical example. It's obviously security-critical. What I mean is that, across all the packages installed on your system, most bugs are fairly irrelevant from the security perspective - i.e., it probably doesn't matter if you can crash uname or ps by passing AAAAAAA... in the command line. /mz
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