Difference between revisions of "CVE-2021-30883"

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(Add info about A14/DCP)
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On {{date|2021|10|11}}, [https://support.apple.com/en-us/HT212623 Apple released iOS 15.0.2] with a fix for CVE-2021-30883, a vulnerability in IOMobileFrameBuffer which allows kernel code execution, and has been exploited in the wild according to Apple. Note that is is not the same as [[CVE-2021-30807]] which was fixed in 14.7.1.
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On {{date|2021|10|11}}, [https://support.apple.com/en-us/HT212623 Apple released iOS 15.0.2] with a fix for CVE-2021-30883, a vulnerability in IOMobileFrameBuffer which allows kernel code execution, and has been exploited in the wild according to Apple. The bug is also present in iOS 15.1 betas 1, 2 and 3. It was fixed in 14.8.1, 15.0.2, and 15.1b4.
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Note that despite also involving IOMFB, this is a different vulnerability than [[CVE-2021-30807]] which was fixed in 14.7.1.
   
 
Saar Amar quickly bindiff'd the kernel and [https://saaramar.github.io/IOMFB_integer_overflow_poc/ wrote a blog post and PoC] about this vulnerability.
 
Saar Amar quickly bindiff'd the kernel and [https://saaramar.github.io/IOMFB_integer_overflow_poc/ wrote a blog post and PoC] about this vulnerability.
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Unlike CVE-2021-30807, this vulnerability is apparently exploitable from the app sandbox without any special entitlement.
 
Unlike CVE-2021-30807, this vulnerability is apparently exploitable from the app sandbox without any special entitlement.
   
Saar's PoC only works on [[A10]]&ndash;[[A13]] devices. Apparently, iOS 15 on A14/A15 moved this code to the [[DCP]]<ref>Tweet from Adam Donenfeld (Zimperium): [https://twitter.com/doadam/status/1447647092055347209 This has been moved to the display coprocessor (DCP) starting from 15, at least on iPhone 12 (and most probably other ones as well)]</ref>. A small change to the PoC causes the DCP coprocessor to panic, which then panics the iOS kernel, but this is unlikely to allow exploiting the kernel.
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Saar's PoC works on [[A10X]], [[A11]], [[A12]], and [[A13]] devices. Apparently, A14/A15 moved this code to the [[DCP]]<ref>Tweet from Adam Donenfeld (Zimperium): [https://twitter.com/doadam/status/1447647092055347209 This has been moved to the display coprocessor (DCP) starting from 15, at least on iPhone 12 (and most probably other ones as well)]</ref>. A small change to the PoC makes it panic the DCP coprocessor, which ''then'' panics the iOS kernel, but this is unlikely to allow exploiting the kernel.
 
(TODO: what about iOS14 on A14?)
 
   
 
== References ==
 
== References ==

Latest revision as of 18:27, 26 October 2021

On 11 October 2021, Apple released iOS 15.0.2 with a fix for CVE-2021-30883, a vulnerability in IOMobileFrameBuffer which allows kernel code execution, and has been exploited in the wild according to Apple. The bug is also present in iOS 15.1 betas 1, 2 and 3. It was fixed in 14.8.1, 15.0.2, and 15.1b4.

Note that despite also involving IOMFB, this is a different vulnerability than CVE-2021-30807 which was fixed in 14.7.1.

Saar Amar quickly bindiff'd the kernel and wrote a blog post and PoC about this vulnerability.

Unlike CVE-2021-30807, this vulnerability is apparently exploitable from the app sandbox without any special entitlement.

Saar's PoC works on A10X, A11, A12, and A13 devices. Apparently, A14/A15 moved this code to the DCP[1]. A small change to the PoC makes it panic the DCP coprocessor, which then panics the iOS kernel, but this is unlikely to allow exploiting the kernel.

References

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