CVE-2019-1128

published 2019-07-15

CVE-2019-1128: 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-2019-1122, CVE-2019-1123, CVE-2019-1124, CVE-2019-1127.

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

• → Trigger path: a specially crafted OpenType variable font with both 'CFF ' and 'CFF2' tables embedded can reach the vulnerable AFDKO readCharset() code via dwrite!AdobeCFF2Snapshot → FontInstancer → dwrite!DWriteFontFace::CreateInstancedStream / dwrite!DWriteFactory::CreateInstancedStream ↗
• → The attack can be triggered via the Direct2D printing interface in Microsoft Edge: a user visiting a page with an embedded malicious OpenType variable font and printing it (to PDF, XPS, or a printer) will execute the vulnerable code path via d2d1!dxc::TextConvertor::InstanceFontResources ↗
• → The PoC font uses a crafted charset descriptor with specific field values to trigger the heap buffer overflow: width=0x02, id=0x4141, nLeft=0xffff. Monitor for OpenType fonts with CFF charset descriptors containing anomalously large nLeft values (e.g. 0xffff / 65535). ↗
• → The exploit technique involves appending a legacy 'CFF ' table to a variable font that already contains a 'CFF2' table. Detection opportunity: scan font files for the simultaneous presence of both 'CFF ' and 'CFF2' tables, which is abnormal and is the prerequisite for reaching the vulnerable code in DirectWrite. ↗
• → Crash/exploitation signature: heap-buffer-overflow write in addID() at cffread.c:1843, called from readCharset() at cffread.c:2187, called from cfrBegFont() at cffread.c:2789. Stack trace pattern can be used for crash triage or sandbox detonation matching. ↗

• · The CreateInstancedStream method used to reach the vulnerable code is not a member of a public COM interface; the known reachable attack surface is via the Direct2D printing interface (e.g. Edge print-to-PDF/XPS). Other trigger paths may exist but were not confirmed. ↗

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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