Date: Wed, 11 May 2016 12:01:19 +0200 From: Hanno Böck <hanno@...eck.de> To: oss-security@...ts.openwall.com Cc: cve-assign@...re.org Subject: ImageMagick heap overflow and out of bounds read https://blog.fuzzing-project.org/45-ImageMagick-heap-overflow-and-out-of-bounds-read.html Recently the ImageTragick vulnerability shed some light on the security status of ImageMagick. This made me wonder how resilient to fuzzing ImageMagick is these days. It's pretty much a posterchild example for a good fuzzing target: Lots of supported complex binary file formats. I already did some fuzzing on ImageMagick, but as far as I remember that was before I used american fuzzy lop and was done with zzuf. I was also aware that others did some more thorough fuzzing on ImageMagick. http://www.openwall.com/lists/oss-security/2014/12/24/1 What I did now was relatively simple: I took a trivial, few pixels PNG and used ImageMagick's "convert" tool to convert it into all file formats that have both read and write support in ImageMagick. I used that to run a fuzzing job with afl and asan. By design ImageMagick will sometimes do huge memory allocations, these can be prevented by setting limits for the width, height and memory usage in the policy.xml file. I discovered one heap buffer overflow in the PICT parser and one heap out of bounds read in the PSD parser. Given how big the attack surface is this is not terrible, but it shows that despite previous efforts there's still potential to fuzz ImageMagick. https://crashes.fuzzing-project.org/imagemagick-heapoverflow-WritePixelCachePixels.pict Sample file for heap buffer overflow in WritePixelCachePixels() (PICT format) https://github.com/ImageMagick/ImageMagick/commit/cfbe890d0cfcd5d3b0f63744a6901e40e992e07c Git commit / fix https://crashes.fuzzing-project.org/imagemagick-oob-heap-read-PushShortPixel.psd Sample file for heap out of bounds read in PushShortPixel() (PSD format) https://github.com/ImageMagick/ImageMagick/commit/15dd190dfd7e7a3341bdc378f4f0daba9873322c Git commit / fix https://www.imagemagick.org/script/changelog.php Both issues have been fixed in the versions 6.9.4-0 and 7.0.1-2. In the meantime new versions (6.9.4-1, 7.0.1-3) came out that, as far as I understand the ChangeLog, remove another potential vector for the ImageTragick vulnerabilities, so you should preferrably update to those. -- Hanno Böck https://hboeck.de/ mail/jabber: hanno@...eck.de GPG: BBB51E42 Content of type "application/pgp-signature" skipped
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