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Watch · Hacking and CTFs

How an Image Causes a Heap Buffer Overflow // libheif

The Brief

  • Explains how uploading an image can trigger a heap buffer overflow in libheif, the HEIF/HEIC image library.
  • Uses the libheif bug involved in the OpenAI Discourse hack as the case study.
  • Visualizes image overlays and clipping, and what goes wrong with negative offsets.
  • Covers how transparency and alpha blending are involved in the overflow.

Why watch · It shows how a malformed image's overlay geometry can cause memory corruption in a widely used image library, relevant to anyone handling user uploads.

  • libheif
  • Heap buffer overflow
  • HEIF/HEIC
  • Discourse

Summarised by Claude from the video’s title and description – no transcript was available, so check the video for the details.

Chapters

  1. 0:00Recap
  2. 1:05What's inside a HEIF or HEIC image?
  3. 3:46Visualizing image overlays and clipping
  4. 5:28What goes wrong with negative offsets?
  5. 7:59alpha blending
  6. 9:37The heap overflow
  7. 11:18Learning with AI
Show the full video description ›

How can uploading an image lead to a heap buffer overflow? Let's look at the libheif bug used in the OpenAI Discourse hack, with a visualization of image overlays, negative offsets, and what goes wrong when transparency is involved. This video is sponsored by Hextree.io, our cybersecurity learning platform. LEARN ON HEXTREE (ad) Learn hacking on Hextree: https://www.hextree.io/ Join the Hextree Discord: https://discord.gg/xgQpCQCpvy PREVIOUS VIDEOS How OpenAI got hacked with an image: https://www.youtube.com/watch?v=gjHh9g7yo9Y OpenAI Hacked with a 1-Year-Old Bug: https://www.youtube.com/watch?v=qypnjORyWNI RESOURCES Hacktron's original research, Hacking OpenAI: https://www.hacktron.ai/blog/hacking-openai libheif source code and format documentation: https://github.com/strukturag/libheif Upstream commit, simplify overlay overlap area computation: https://github.com/strukturag/libheif/commit/85e21ad44eba931314337300a2376b8d28f085ae Discourse security advisory: https://github.com/discourse/discourse/security/advisories/GHSA-vhm9-85gw-x335 CHAPTERS 00:00 - Recap 01:05 - What's inside a HEIF or HEIC image? 03:46 - Visualizing image overlays and clipping 05:28 - What goes wrong with negative offsets? 07:59 - alpha blending 09:37 - The heap overflow 11:18 - Learning with AI SUPPORT Per video: https://www.patreon.com/join/liveoverflow Per month: https://www.youtube.com/channel/UClcE-kVhqyiHCcjYwcpfj9w/join Buy my handwriting font (ad): https://shop.liveoverflow.com/ WATCH, FOLLOW & READ Second channel: https://www.youtube.com/LiveUnderflow Twitch: https://twitch.tv/LiveOverflow/ Twitter: https://twitter.com/LiveOverflow/ Instagram: https://instagram.com/LiveOverflow/ TikTok: https://www.tiktok.com/@liveoverflow_ LiveOverflow blog: https://liveoverflow.com/ Hextree blog (ad): https://www.hextree.io/blog #BinaryExploitation #LiveOverflow (ad) LiveOverflow YouTube channel is supported by advertisement and product placement.