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.”
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.