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Microsoft Patches Code Execution, Privilege Escalation Flaws in Azure Sphere

Recently addressed Microsoft Azure Sphere vulnerabilities could lead to the execution of arbitrary code or to elevation of privileges, Cisco Talos’ researchers warn.

The cloud-based system on a chip (SoC) platform was designed for Internet of Things (IoT) security, and is comprised of a hardware platform (several ARM cores, each with a different role), Azure Sphere OS (custom, Linux-based OS), and the Azure Sphere Security Service (for continuous security).

Talos’ security researchers discovered a total of four vulnerabilities in Azure Sphere, two of which could lead to the execution of unsigned code, and two leading to privilege escalation. All bugs were addressed, although no CVEs were issued.

According to Talos, both of the code execution flaws affect “the normal world’s signed code execution functionality of Microsoft Azure Sphere.”

The first of them resides in the Normal World application READ_IMPLIES_EXEC personality and can be triggered through specially crafted shellcode that would cause a process’ writable heap to become executable.

The second of them was found in /proc/thread-self/mem and can be exploited via specially crafted shellcode designed to cause a process' non-writable memory to be written to. Thus, the attacker could supply shellcode designed to modify the program and trigger the bug.

Cisco Talos’ security researchers discovered a privilege escalation issue in the Capability access control functionality and reveal that an attacker could leverage shellcode to target the vulnerability and gain elevated privileges via specially crafted ptrace syscalls.

As for the second elevation of privilege bug, it was discovered in the uid_map functionality of Microsoft Azure Sphere 20.06 and can be abused through a specially crafted uid_map file.

By causing multiple applications to have the same UID, an attacker could ensure that a user application is executed with a system application’s UID.

The first of the vulnerabilities was found in version 20.07 of Azure Sphere, while the other three were discovered in version 20.06. Microsoft has published a blog post detailing the improvements and fixes included in Azure Sphere 20.08, which patches the vulnerabilities.

Related: Microsoft Offering Up to $100,000 for Vulnerabilities in Azure Sphere

Related: Microsoft Launches Azure Security Center for IoT

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