Researcher Drops 3 Separate 0-Day Windows Exploits in 24 Hours

SandboxEscaper, the security researcher who posted a claimed zero-day Windows 10 vulnerability on GitHub Tuesday, has now posted the remaining four exploits (two yesterday and the final two today) that he or she (we’ll say ‘she’) said she possessed. 

This is not the first time that Sandbox Escaper has publicly disclosed Windows 0-days.

The four new exploits are described as AngryPolarBearBug2, SandboxEscape, InstallerBypass and CVE-2019-0841-BYPASS. All four are claimed as zero-days because they are unpatched, but their severity is not high. At least one, AngryPolarBearbug2, is not a zero-day, having been patched at the same time as the first was patched.

SandboxEscaper had offered to sell LPEs (low probability for exploitation) for “60k for an LPE” on her blog — provided it was to ‘non-western people’. She later added, “I have most definitely given portions of my work to people who hate the US.”

AngryPolarBearbug2 is similar to the first (non)zero-day posted two days ago, but now exploiting a race condition between two function calls in Windows Error Reporting. It is a local privilege escalation exploit, so local access is again required. It is also difficult to activate, with some researchers already reporting their failure to do so. “It is just an insanely small window in which we can win our race, I wasn’t even sure if I could ever exploit it at all,” said SandboxEscaper.

The vulnerability has an assigned CVE: CVE-2019-0863. Researcher Gal De Leon, who is credited with finding CVE-2019-0863, tweeted, “The race is quite difficult to win but possible, and it provides a primitive to overwrite the DACL of an arbitrary file.” However, like the first exploit (bearlpe), this has already been patched by Microsoft. @0patch commented, “SandboxEscaper’s “angrypolarbearbug2″ vulnerability published yesterday is not a 0day. It’s been patched with May Windows Updates.”  

However, 0patch continued, “In contrast, we’re confirming that “sandboxescape”, the other SandboxEscaper’s vulnerability published yesterday, does work on fully updated Windows 10, allowing malicious code executing inside sandboxed iexplore.exe (Low or AppContainer integrity) to elevate to Medium integrity.”

With this exploit, an attacker could inject a DLL into a specified Internet Explorer process. This could activate JavaScript, that disables Internet Protected mode. Again, it requires local access. It doesn’t present a direct threat, but allows a malicious web site exploiting some RCE vuln to escape from Internet Explorer’s sandbox.

Today’s final two exploits are InstallerBypass and CVE-2019-0841-BYPASS. InstallerBypass also exploits a race condition in MSI installers to trigger a rollback. “It’s a really hard race, doubt anyone will be able to repro anyway,” comments SandboxEscaper, adding, “Could be used with malware, you could programmatically trigger the rollback.”

CVE-2019-0841-BYPASS relates to a remaining bug in the code triggered by CVE-2019-0841. The effect is to make win.ini write-able. Rich Warren, principal security consultant at the NCC Group, has confirmed that it “is indeed a 0day and works up to the latest 1903 build (but no collector abuse anymore).” He has produced a ‘weaponized demo’.

With posting the last two exploits today, SandboxEscaper blogged, “Uploaded the remaining bugs. I like burning bridges. I just hate this world.” Her blog is full of personal despair and depression, and hatred for the west in general, and the U.S and the FBI in particular. It proves nothing, of course, because on the internet anybody can be anything.

Related: Windows Zero-Day Exploited in Targeted Attacks by ‘PowerPool’ Group 

Related: Microsoft Patches Windows Zero-Day Disclosed via Twitter 

Related: Exploit for New Windows Zero-Day Published on Twitter

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Kevin Townsend is a Senior Contributor at SecurityWeek. He has been writing about high tech issues since before the birth of Microsoft. For the last 15 years he has specialized in information security; and has had many thousands of articles published in dozens of different magazines – from The Times and the Financial Times to current and long-gone computer magazines.

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