CVE-2019-1122

published 2019-07-15

CVE-2019-1122: A remote code execution vulnerability exists in the way that DirectWrite handles objects in memory, aka 'DirectWrite Remote Code Execution Vulnerability'. This…

Priority P2 65 high 8.8 CVSS 3.0

AV N AC L PR N UI R S U C H I H A H

EXPLOIT

A remote code execution vulnerability exists in the way that DirectWrite handles objects in memory, aka 'DirectWrite Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2019-1117, CVE-2019-1118, CVE-2019-1119, CVE-2019-1120, CVE-2019-1121, CVE-2019-1123, CVE-2019-1124, CVE-2019-1127, CVE-2019-1128.

Affected

36 ranges · showing 25

Vendor	Product	Version range	Fixed in
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows	—	—
microsoft	windows_10	—	—
microsoft	windows_10	—	—
microsoft	windows_10	—	—
microsoft	windows_10	—	—
microsoft	windows_10_version_1903_for_32-bit_systems	—	—
microsoft	windows_10_version_1903_for_arm64-based_systems	—	—
microsoft	windows_10_version_1903_for_x64-based_systems	—	—
microsoft	windows_server	—	—
microsoft	windows_server	—	—
microsoft	windows_server	—	—
microsoft	windows_server_2016	—	—
microsoft	windows_server_2016	—	—
msrc	windows_10_version_1709_for_32-bit_systems	—	—
msrc	windows_10_version_1709_for_arm64-based_systems	—	—
msrc	windows_10_version_1709_for_x64-based_systems	—	—
msrc	windows_10_version_1803_for_32-bit_systems	—	—

Detection & IOCs extracted from sources · hover to see the quote

path afdko/c/public/lib/source/cffread/cffread.c↗

filename poc.otf↗

command ./tx -cff poc.otf↗

• → The vulnerability is triggered via the Direct2D printing interface in Microsoft Edge; monitor for Edge processes initiating print operations (to PDF, XPS, or physical/virtual printers) that load OpenType variable fonts, as this invokes dwrite!AdobeCFF2Snapshot via FontInstancer. ↗
• → Look for call stacks involving dwrite!AdobeCFF2Snapshot → FontInstancer → dwrite!DWriteFontFace::CreateInstancedStream or dwrite!DWriteFactory::CreateInstancedStream → d2d1!dxc::TextConvertor::InstanceFontResources as indicators of exploitation attempt. ↗
• → Detect specially crafted OTF files that contain both a valid CFF2 table and a malformed/extra CFF table; the malicious CFF table takes precedence over CFF2 in AFDKO's srcOpen() logic and triggers the heap buffer overflow in readStrings(). ↗

• · The integer overflow in readStrings() (cffread.c:1738) is only exploitable on platforms where 'long' is a 32-bit type, limiting the attack surface to Windows x86/x64 and Linux x86 builds. ↗
• · The CreateInstancedStream method is not a public COM interface; the known reachable attack path is exclusively through d2d1!dxc::TextConvertor::InstanceFontResources (e.g., Edge printing). Other attack vectors may exist but are unconfirmed. ↗

CVSS provenance

nvd v3.0 8.8 HIGH CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd v2.0 9.3 CRITICAL AV:N/AC:M/Au:N/C:C/I:C/A:C

vendor_msrc 7.8 HIGH

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