Researcher Publishes Four Zero-Day Exploits in Three Days

A vulnerability researcher published four previously unreported flaws in Microsoft Windows over three days this week, flaws that could allow a local user to escalate their rights on a compromised system to that of an administrator.

Exploits for the four flaws — plus a fifth vulnerability that Microsoft fixed last week — were posted by the researcher to a GitHub repository using the name SandboxEscaper. The researcher, who has published working zero-day attacks for legitimate vulnerabilities in the past, posted the first exploit on Tuesday, May 21, with two more exploits published on each of the next two days.

The danger from the issues is likely to be low, but the code could be incorporated into popular malware frameworks, says Craig Young, a computer security researcher with Tripwire's Vulnerability and Exposure Research Team (VERT).

"Overall, these vulnerabilities do not markedly change the typical security advice to use a layered approach to security, including endpoint monitoring," he says. "Unlike the Task Scheduler exploit disclosed earlier in the week, these bugs do not require the attacker to know a username and password — meaning that some of them could more realistically be incorporated into malware."

Publishing, or "dropping," unknown vulnerabilities and exploit code used to be a popular way for vulnerability researchers to punish software vendors for a lack of focus on software security or for a lack of response to researchers' vulnerability reports. However, as companies have increasingly taken security more seriously, and the impact of exploited vulnerabilities has grown more dire, researchers are far more likely to cooperate with software makers to fix issues, in a process known as coordinated disclosure.

Microsoft and the researcher may have collaborated on one of the issues, which resulted in the software giant fixing it earlier this month during its regular Patch Tuesday release. In a bulletin, Microsoft stated it had fixed the issue, identified as CVE-2019-0863, and credited both Palo Alto Networks and PolarBear, one name associated with SandboxEscaper. The GitHub repository that hosted the exploits published by the researcher was called PolarBearRepo.

Following the posting of the four other exploits, however, Microsoft was more circumspect.

"Microsoft has a customer commitment to investigate reported security issues and we will provide updates for impacted devices as soon as possible," the company said in a statement. "We urge finders to practice coordinated vulnerability disclosure to reduce the potential risk to customers.”

SandboxEscaper published five exploits on GitHub. On Tuesday, the researcher published a code snippet called BearLPE, which exploits the Task Schedule to escalate local privileges. Local privilege escalations are techniques in which the attacker gains more capabilities on the targeted system by circumventing the operating system protections around user roles.

On Wednesday, the researcher published two more exploits, including one called AngryPolarBearBug2, which targeted the issue Microsoft patched the week before. The researchers followed on Thursday with another two exploits.

While the issues are mostly straightforward to exploit, two vulnerabilities are a type of vulnerability known as a race condition, and they require specific action to be conducted within a very tight time frame, making them more difficult to use successfully, says Satnam Narang, a senior research engineer at security firm Tenable.

"Some of these zero days are really hard to exploit, and some are a matter of having certain policies in place to address them, of having certain products and security tools," he says.

Because the exploits cannot be used remotely, they are not as dangerous as some attacks, says Tripwire's Young.

"Similar to past SandboxEscaper releases, these exploits are also local privilege escalations, meaning that attackers would use these only after gaining a foothold on a targeted system," he says.

SandboxEscaper has gained a reputation for releasing LPE exploits with no warning. The researcher has posted repeatedly of her dislike for the software and security industries.

"F--- this s----- industry. I don't plan to make a career in it anyway," she wrote in a post on Wednesday. "I hate all the people involved in this industry. Everyone just thinks they know better. Everyone just loves pointing fingers."

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