ELEGANTBOUNCER is a detection tool for file-based mobile exploits. It employs an innovative approach for advanced file-based threat identification, eliminating the need for in-the-wild samples and outperforming traditional methods based on regular expressions or IOCs. At present, it primarily targets the identification of mobile vulnerabilities such as FORCEDENTRY (CVE-2021-30860), BLASTPASS (CVE-2023-4863, CVE-2023-41064), and TRIANGULATION (CVE-2023-41990) [and recently added CVE-2025-43300].
> While reproducing the iOS ITW CVE-2025-43300 (support.apple.com/en-us/124925), we accidentally triggered another old DNG image parsing vulnerability. The analysis is still ongoing.
Traditional detection approaches like YARA rules, IOC matching, and signature-based systems fall apart when:
• You don’t have the actual malicious samples to create signatures from
• The attackers use polymorphic techniques that change file hashes
• The exploit leverages legitimate file format features in unexpected ways
• You need to detect future variants of the same technique
The Philosophy: Structure Over Signatures
ELEGANTBOUNCER takes a fundamentally different approach to threat detection. Instead of looking for specific byte patterns or known-bad indicators, it analyzes the structural properties of files that make exploits possible.
Note that even though the CVE is for a RCE (remote code execution)[1], this specific PoC is at most a DoS (denial of service). There's more work needed to bypass mitigations for it to be actually usable as a RCE.
> This blog post discusses an old type of issue, vulnerabilities in image format parsers, in a new(er) context: on interactionless code paths in popular messenger apps. This research was focused on the Apple ecosystem and the image parsing API provided by it: the ImageIO framework. Multiple vulnerabilities in image parsing code were found, reported to Apple or the respective open source image library maintainers, and subsequently fixed. During this research, a lightweight and low-overhead guided fuzzing approach for closed source binaries was implemented and is released alongside this blogpost.
> I used LLDB to examine the testHeader functions, it turned out there are three new testHeader functions for different file formats, such as KTX2 and WebP and ETC, so because they were fairly new I thought maybe they have not been fuzzed by Project Zero... I ported Project Zero’s harness to Jackalope fuzzer.. My fuzzing effort found several vulnerabilities [fixed by Apple]..
Lots of experience in what are common exploit tactics are and where to look and test if things will break.
Identifying an exploit in iOS requires a significant amount of knowledge in how the OS works, what existing exploits are and how you could chain them together to create a larger exploit.
I've have very limited experience, but reading about how some people identify and exploit these things is extremely impressive.
is it me or does ios have a myriad of cves in in the image processing/decoder stack? You'd think they'd sandbox in some kind of memory safe framework/lang by now?
unfortunately sandboxes also have bugs which allows for RCE. this is typically called a "full chain" because it chains together a series of bugs (initial decoder exploit + sandbox escape exploit) to gain full RCE
Surprised to see no patch available for watchOS, which can also receive images via iMessage. Not important enough to patch, or not vulnerable, or just not exploited in the wild yet?
The DNG file did have the 01 byte at `2FD00` (from xxd or hexdump -C). However it didn't have a byte position `3E40B`. I tried searching and there is literally no entry at that position. I found a 02 value at 3e40 but not at 3e40b. Is this a typo?
Thanks! You are correct, when I did a dump with `xxd IMGP0847.DNG > output.hex` it wasn't showing up for some reason.... But your command worked (though my dd doesn't like hex values so I needed to get decimal via printf "%d\n" 0x3E40B).
Curious if you (clearly smarter than me) know why it didn't show correctly in the xxd or hexdump for the file. Would love to learn.
I'm actually really curious about how the ITW exploit for this CVE worked; the OOB write is quite obvious in hindsight but going from OOB write to execution on iOS is very much not easy these days, and going from OOB write to sandbox escape should be extremely hard, especially since I thought (?) all image previews in iMessage should be behind BlastDoor. There's a lot of interesting stuff that's still missing here.
> I'm actually really curious about how the ITW exploit for this CVE worked
It's really weird to see only a single OOB write patched for a full 0-click chain in the wild - how did they get code execution? PAC+ASLR bypass? Sandbox escape/kernel escalation?
Literally only RawCamera is patched in the update - were the other bugs in the chain already patched? Too difficult to patch immediately? (ie - close the front door while working on replacing the other locks?)? Still unknown? (ie - found a crash dump from RawCamera but didn't get as sample of the full chain?)
This might be a weird corner case where Apple would outbid the grey market, but generally even though Apple comes in lower than the grey market (for these very specific kinds of vulnerabilities), the term sheets are different, and the rest of the terms tend to favor going with Apple.
It's 2025, and Apple clearly still hasn't incorporated fuzzers in their CI and QA. Perhaps I am giving them too much credit in assuming they have any QA in the first place.
Seems like it was major enough that it was the lone patch[0] in all active Apple OS's:
macOS Ventura 13.7.8 | macOS Sonoma 14.7.8 | macOS Sequoia 15.6.1
iPadOS 17.7.10 | iPadOS 18.6.2 | iOS 18.6.2
Usually, its multiple CVE's in a security update.
Examples:
- https://support.apple.com/en-us/122375 (macOS Ventura 13.7.5)
- https://support.apple.com/en-us/122718 (macOS Ventura 13.7.6)
- https://support.apple.com/en-us/124151 (macOS Ventura 13.7.7)
--------------------------- References/Sources ---------------------------
[0] https://support.apple.com/en-us/124925 -> https://support.apple.com/en-us/124929 | (124925 -> 124929)
https://support.apple.com/en-us/100100
https://nvd.nist.gov/vuln/detail/CVE-2025-43300#vulnConfigur...
For iOS defense, enable Lockdown Mode and reboot daily to evict non-persistent malware, https://www.youtube.com/watch?v=fAhTPMmvrB0
> For me, there is only lockdown mode. That is the Apple Experience.
iOS backups can be scanned for the presence of this CVE-2025-43300 DNG processing vulnerability, via OSS tool for iOS forensics, https://github.com/msuiche/elegant-bouncer | https://www.msuiche.com/posts/elegantbouncer-when-you-cant-g...
https://x.com/darknavyorg/status/1959271176062251333> While reproducing the iOS ITW CVE-2025-43300 (support.apple.com/en-us/124925), we accidentally triggered another old DNG image parsing vulnerability. The analysis is still ongoing.
I would think mvt and related ioc repos would support these newer indicators,but sadly I'm not seeing that:
https://docs.mvt.re/en/latest/iocs/
It's a different approach:
Note that even though the CVE is for a RCE (remote code execution)[1], this specific PoC is at most a DoS (denial of service). There's more work needed to bypass mitigations for it to be actually usable as a RCE.
[1] https://support.apple.com/en-us/124925
How do people even find these types of bugs? Is it just years and years experience allowing you to know where to look?
Fuzzing is one approach.
"Fuzzing ImageIO" (2020), https://googleprojectzero.blogspot.com/2020/04/fuzzing-image...
> This blog post discusses an old type of issue, vulnerabilities in image format parsers, in a new(er) context: on interactionless code paths in popular messenger apps. This research was focused on the Apple ecosystem and the image parsing API provided by it: the ImageIO framework. Multiple vulnerabilities in image parsing code were found, reported to Apple or the respective open source image library maintainers, and subsequently fixed. During this research, a lightweight and low-overhead guided fuzzing approach for closed source binaries was implemented and is released alongside this blogpost.
"ImageIO, the infamous iOS Zero Click Attack Vector" (2024), https://r00tkitsmm.github.io/fuzzing/2024/03/29/iOSImageIO.h...
> I used LLDB to examine the testHeader functions, it turned out there are three new testHeader functions for different file formats, such as KTX2 and WebP and ETC, so because they were fairly new I thought maybe they have not been fuzzed by Project Zero... I ported Project Zero’s harness to Jackalope fuzzer.. My fuzzing effort found several vulnerabilities [fixed by Apple]..
Lots of experience in what are common exploit tactics are and where to look and test if things will break.
Identifying an exploit in iOS requires a significant amount of knowledge in how the OS works, what existing exploits are and how you could chain them together to create a larger exploit.
I've have very limited experience, but reading about how some people identify and exploit these things is extremely impressive.
is it me or does ios have a myriad of cves in in the image processing/decoder stack? You'd think they'd sandbox in some kind of memory safe framework/lang by now?
Look up iMessage's "blastdoor" sandbox: https://support.apple.com/guide/security/blastdoor-for-messa...
FORCEDENTRY bypassed this sandbox IIRC. That was a bug in the JBIG2 decoder.
unfortunately sandboxes also have bugs which allows for RCE. this is typically called a "full chain" because it chains together a series of bugs (initial decoder exploit + sandbox escape exploit) to gain full RCE
For some reason, Apple seems reluctant about using Rust on their operating systems.
That reason is probably called Swift. But they obviously still have many many system libraries written in Objective-C, plain C or C++.
I don't see them using Rust when they have their own language under their full control, especially since both are targeting LLVM anyway.
Surprised to see no patch available for watchOS, which can also receive images via iMessage. Not important enough to patch, or not vulnerable, or just not exploited in the wild yet?
I AirDropped the PoC to my vulnerable iPhone. It didn't cause a crash until I tried to edit it in the Photos app.
I downloaded the image he provided (https://www.dpreview.com/sample-galleries/4949897610/pentax-...)
The DNG file did have the 01 byte at `2FD00` (from xxd or hexdump -C). However it didn't have a byte position `3E40B`. I tried searching and there is literally no entry at that position. I found a 02 value at 3e40 but not at 3e40b. Is this a typo?
Where did you find it to try and repro?
You need to click the link that says "RAW (33.0MB)". The filename should be "IMGP0847.DNG".
Thanks immensely. Very important detail,
Did you find a 02 at 3E40B? I found 01 at 2FD00, but there was no 3E40B byte position entry.
I did find something similar at 00003e40: 00003e40 02 00 04 00 0a 00 00 00 30 01 00 00 00 00 00 00 |........0.......|
Yes:
Thanks! You are correct, when I did a dump with `xxd IMGP0847.DNG > output.hex` it wasn't showing up for some reason.... But your command worked (though my dd doesn't like hex values so I needed to get decimal via printf "%d\n" 0x3E40B).
Curious if you (clearly smarter than me) know why it didn't show correctly in the xxd or hexdump for the file. Would love to learn.
Maybe you need to iMessage it to someone else? Just guessing.
https://web.archive.org/web/20250827063813/https%3A%2F%2Fs3....
Where's the 0-click or the RCE here?
I'm actually really curious about how the ITW exploit for this CVE worked; the OOB write is quite obvious in hindsight but going from OOB write to execution on iOS is very much not easy these days, and going from OOB write to sandbox escape should be extremely hard, especially since I thought (?) all image previews in iMessage should be behind BlastDoor. There's a lot of interesting stuff that's still missing here.
>Where's the 0-click or the RCE here?
See my other comment. There's an exploit in the wild that uses this bug to get RCE, but this specific example just causes a crash.
Yes, that's what I'm referring to with
> I'm actually really curious about how the ITW exploit for this CVE worked
It's really weird to see only a single OOB write patched for a full 0-click chain in the wild - how did they get code execution? PAC+ASLR bypass? Sandbox escape/kernel escalation?
Literally only RawCamera is patched in the update - were the other bugs in the chain already patched? Too difficult to patch immediately? (ie - close the front door while working on replacing the other locks?)? Still unknown? (ie - found a crash dump from RawCamera but didn't get as sample of the full chain?)
I wonder how much this would be worth for Zerodium
$0, given it's patched in ios 18.6.2
And given that Zerodium has shut down.
Its website still works and there's a gpg key, so it's a "shutdown" rather than shutdown.
Before that obviously. Possibly pc meant to ask if the “finder” would have gone to them instead of dealing with Apple directly.
The AirDrop requirement probably decreases its value substantially, but I think all these kinds of questions are kind of tricky to reason about:
https://news.ycombinator.com/item?id=43025038
This might be a weird corner case where Apple would outbid the grey market, but generally even though Apple comes in lower than the grey market (for these very specific kinds of vulnerabilities), the term sheets are different, and the rest of the terms tend to favor going with Apple.
$0, since I don't think Zerodium still exists.
Oh, so we'll get another jailbreak soon? Wow, thanks [whatever Israeli agency/company is behind this] :)
Does this affect any of the iOS, iPadOS macOS, tvOS, watchOS 26 Beta?
Apple patched it on August 20, so presumably any release from after this date is not vulnerable.
Dang that's so cool!
It's 2025, and Apple clearly still hasn't incorporated fuzzers in their CI and QA. Perhaps I am giving them too much credit in assuming they have any QA in the first place.
ImageIO has been fuzzed by Google and others, https://news.ycombinator.com/item?id=45034650
I have no idea what you're talking about; Apple has one of the largest and most sophisticated software security practices on the planet.
They do, but unfortunately it is built on top of a shacky foundation.