WARNING: Google Discloses Windows Zero
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-15999 | Heap Buffer Overflow in FreeType Font Rendering in Google Chrome (CVE-2020-15999) Google Chrome bundles the open-source FreeType library for font rendering, and that library contains a heap buffer overflow (CWE-787, out-of-bounds write) in its Load_SBit_Png function. The flaw is triggered when the browser loads a crafted font containing a malicious PNG image embedded as embedded bitmap data, typically from a web page the victim visits, corrupting heap memory with attacker-controlled data. Successful exploitation can crash the browser or execute code in the renderer, and it was used in the wild as part of an exploit chain combined with CVE-2020-17087 (Windows kernel) and CVE-2020-16010 (Android) to escape the sandbox. Anyone running an affected Google Chrome release that ships the vulnerable FreeType code, across Windows, macOS, Linux, Chrome OS and Android, is affected, meaning effectively the entire Chrome install base at the time of disclosure. The vulnerability is confirmed exploited in the wild (listed in CISA's KEV catalog, added 2021-11-03; ransomware use unknown), Google patched it in Chrome 86.0.4240.111, no public proof-of-concept is known, and EPSS estimates a 44.3% probability of exploitation within 30 days (99th percentile). Do: Update Google Chrome to 86.0.4240.111 or later (any current stable-channel release satisfies this), and where other software bundles FreeType directly, update to FreeType 2.10.4 or later per the upstream fix. Because the bug was chained with CVE-2020-17087 on Windows and CVE-2020-16010 on Android, also apply the corresponding Microsoft Windows and Android updates to close the sandbox-escape chain. Use endpoint management to inventory browser versions and confirm no endpoints remain below the fixed release, as required by the CISA KEV catalog. | 9.6 | 44% | KEV PoC ×2 |
| masson the order of billions of users (Chrome's active user base exceeded ~3 billion at the time; the vulnerable FreeType code shipped in every affected release) | |
| CVE-2020-17087 | Windows Kernel Buffer Overflow Enables Local Privilege Escalation (CVE-2020-17087) CVE-2020-17087 is a local elevation-of-privilege flaw in the Windows kernel caused by an incorrect buffer size calculation (CWE-131), producing a kernel buffer overflow; public analyses from Microsoft and Google's disclosure place the vulnerable code in the kernel's cryptographic driver (cng.sys). A local attacker with low privileges can trigger the overflow without user interaction, gaining code execution in kernel context and effectively full control of the host (high impact on confidentiality, integrity, and availability; CVSS 7.8). Every Windows system on the affected builds is exposed: Windows 10 versions 1507 through 20H2, Windows 7, 8.1, RT 8.1, and Windows Server 2008, which at disclosure meant essentially the entire supported Windows install base. The flaw was exploited as a zero-day in the wild: Google disclosed its use in targeted attacks, reportedly chained with a Chrome zero-day, and CISA added it to the KEV catalog on 2021-11-03; EPSS currently estimates a 5.4% probability of exploitation within 30 days (92nd percentile), with ransomware association listed as unknown. Do: Apply Microsoft's November 2020 Patch Tuesday security updates to all affected Windows 10, Windows 7, 8.1, RT 8.1, and Windows Server 2008 systems; this is CISA's required action for the KEV listing and no official workaround is known. Prioritize hosts where untrusted users can log on locally or via RDP, and ensure Chromium-based browsers are fully updated since this kernel bug was reportedly chained with a Chrome zero-day. After patching, verify the November 2020 update is installed; treat any ransomware association as currently unconfirmed. | 7.8 | 5% | KEV |
| mass≈1 billion+ devices (essentially the entire supported Windows install base at disclosure) |
Full article363 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananNov 02, 2020
Google has disclosed details of a new zero-day privilege escalation flaw in the Windows operating system that's being actively exploited in the wild.
The elevation of privileges (EoP) vulnerability, tracked as CVE-2020-17087, concerns a buffer overflow present since at least Windows 7 in the Windows Kernel Cryptography Driver ("cng.sys") that can be exploited for a sandbox escape.
"The bug resides in the cng!CfgAdtpFormatPropertyBlock function and is caused by a 16-bit integer truncation issue," Google's Project Zero researchers Mateusz Jurczyk and Sergei Glazunov noted in their technical write-up.
The security team made the details public following a seven-day disclosure deadline because of evidence that it's under active exploit.
Project Zero has shared a proof-of-concept exploit (PoC) that can be used to corrupt kernel data and crash vulnerable Windows devices even under default system configurations.
What's notable is that the exploit chain requires linking CVE-2020-17087 with another Chrome browser zero-day (CVE-2020-15999) that was fixed by Google last week.
The Chrome zero-day involves a heap buffer overflow in the Freetype font library to run malicious code in the browser, but the newly revealed Windows zero-day makes it possible for an attacker to break out of Chrome's sandbox protections and run the code on Windows — also called a sandbox escape.
Stating that the exploitation is "not related to any US election-related targeting," Project Zero's Ben Hawkes said a patch for the flaw is expected to be released by Microsoft on November 10.
Hawkes also defended the practice of disclosing zero-days within a week of them being actively exploited.
"We think there's defensive utility to sharing these details, and that opportunistic attacks using these details between now and the patch being released is reasonably unlikely (so far it's been used as part of an exploit chain, and the entry-point attack is fixed)," he said.
"The short deadline for in-the-wild exploit also tries to incentivize out-of-band patches or other mitigations being developed/shared with urgency. Those improvements you might expect to see over a longer term period," Hawkes added.
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Text extracted automatically; images, tables and formatting may be missing. Original: https://thehackernews.com/2020/11/warning-google-discloses-windows-zero.html