Uploaded December 2023 | Updated September 2026, 2 weeks ago

---

Citizenlab discovered BLASTPASS, a 0day being actively exploited in the image format WebP. Known as CVE-2023-4863 and CVE-2023-41064, an issue in webp's build huffman table function can lead to a heap buffer overflow. This vulnerability is very interesting and I'm excited to share with you what I learned.


LEARN ON HEXTREE (ad)
Learn hacking on Hextree: hextree.io
Join the Hextree Discord: discord.gg/xgQpCQCpvy

WebP Fix Commit: chromium.googlesource.com/webm/libwebp/+/902bc9190331343b2017211debcec8d2ab87e17a
Citizenlab: citizenlab.ca/2023/09/blastpass-nso-group-iphone-zero-click-zero-day-exploit-captured-in-the-wild
Ben Hawkes: blog.isosceles.com/the-webp-0day

Software Updates
Apple support.apple.com/en-gb/106361
Chrome chromereleases.googleblog.com/2023/09/stable-channel-update-for-desktop_11.html
Firefox mozilla.org/en-US/security/advisories/mfsa2023-40
Android source.android.com/docs/security/bulletin/2023-10-01
Whose CVE is it Anyway? adamcaudill.com/2023/09/14/whose-cve-is-it-anyway

References:
2014 bug introduction github.com/webmproject/libwebp/commit/f75dfbf23d1df1be52350b1a6fc5cfa6c2194499
youtube.com/watch?v=JsTptu56GM8
youtube.com/watch?v=B3y0RsVCyrw
youtube.com/watch?v=EFUYNoFRHQI
youtube.com/watch?v=iEm1NRyEe5c
stackoverflow.com/questions/13804629/huffman-code-with-lookup-table
web.archive.org/web/20230204211844/https://commandlinefanatic.com/cgi-bin/showarticle.cgi?article=art007
enough.c github.com/madler/zlib/blob/develop/examples/enough.c

Thanks to:
twitter.com/mistymntncop
twitter.com/benhawkes

CHAPTERS
00:00 - Intro to CVE-2023-4863
01:32 - Most Valuable Vulnerability?
03:02 - Heap Overflow Related to Huffman Trees
03:58 - Learning about Huffman Codes
06:24 - What are Huffman Tables?
10:24 - Hardcoded Table Sizes (enough.c)
12:21 - Code Walkthrough - BuildHuffmanTable()
13:04 - The code_lengths[] and count[] Arrays
15:14 - Difference Between Compression and Decompression!
17:04 - Outro

SUPPORT
Per video: patreon.com/join/liveoverflow
Per month: youtube.com/channel/UClcE-kVhqyiHCcjYwcpfj9w/join
Buy my handwriting font (ad): shop.liveoverflow.com

WATCH, FOLLOW & READ
Second channel: youtube.com/LiveUnderflow
Twitch: twitch.tv/LiveOverflow
Twitter: twitter.com/LiveOverflow
Instagram: instagram.com/LiveOverflow
TikTok: tiktok.com/@liveoverflow_
LiveOverflow blog: liveoverflow.com
Hextree blog (ad): hextree.io/blog

#BufferOverflow #SecurityResearch #LiveOverflow

(ad) LiveOverflow YouTube channel is supported by advertisement and product placement.