cbcvebase.
CVE-2018-4200
published 2018-06-08

CVE-2018-4200: An issue was discovered in certain Apple products. iOS before 11.3.1 is affected. Safari before 11.1 is affected. iCloud before 7.5 on Windows is affected…

PriorityP263high8.8CVSS 3.0
AVNACLPRNUIRSUCHIHAH
EXPLOIT
EPSS
8.73%
94.6th percentile
An issue was discovered in certain Apple products. iOS before 11.3.1 is affected. Safari before 11.1 is affected. iCloud before 7.5 on Windows is affected. iTunes before 12.7.5 on Windows is affected. tvOS before 11.4 is affected. The issue involves the "WebKit" component. It allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted web site that triggers a WebCore::jsElementScrollHeightGetter use-after-free.

Affected

27 ranges· showing 25
VendorProductVersion rangeFixed in
appleicloud< 7.57.5
appleicloud_for_windows
appleios
appleiphone_os< 11.3.111.3.1
appleitunes< 12.7.512.7.5
appleitunes_12.7.5_for_windows
applesafari< 11.111.1
applesafari
appletvos< 11.411.4
appletvos
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
debianwebkit2gtk< webkit2gtk 2.20.2-1 (bookworm)webkit2gtk 2.20.2-1 (bookworm)
f5big-ip_aam
f5big-ip_afm
f5big-ip_analytics
f5big-ip_apm
f5big-ip_asm
f5big-ip_dns
f5big-ip_edge_gateway
f5big-ip_gtm
f5big-ip_link_controller
f5big-ip_ltm
f5big-ip_pem

Detection & IOCsextracted from sources · hover to see the quote

commandinput:enabled { content: url(#foo); padding-top: 0vmin }
command.class4 { -webkit-transform: scale(1, 255); }
commandvar test = input.scrollHeight;
  • The use-after-free is triggered via access to the scrollHeight property on an input element after a DOM manipulation (appendChild) causes the underlying RenderStyle object to be freed; monitor for JavaScript accessing .scrollHeight on input elements in conjunction with dynamic DOM mutations.
  • The exploit PoC combines a CSS content property referencing an internal fragment URL (url(#foo)) on an :enabled input with a -webkit-transform scale rule; detection of this CSS pattern in web content may indicate exploitation attempts.
  • Crash stack trace shows the fault originates in WebCore::jsElementScrollHeightGetter -> WebCore::adjustForAbsoluteZoom -> WebCore::RenderStyle::effectiveZoom -> WebCore::DataRef::operator->; a crash in this call chain on unpatched WebKit versions is a strong indicator of CVE-2018-4200 exploitation.
  • The freed memory region is 320 bytes; heap forensics showing a 320-byte freed allocation accessed 120 bytes inside it during a scrollHeight getter call is indicative of this UAF.
  • ·The exploit PoC was developed and tested against a local debug build of WebKit; offsets and addresses in the stack trace are specific to that build and are not directly portable to production binaries.

CVSS provenance

nvdv3.08.8HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
nvdv2.06.8MEDIUMAV:N/AC:M/Au:N/C:P/I:P/A:P
osv8.8HIGH
vendor_debian8.8LOW
vendor_redhat8.8HIGH
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