Flatpak apply_extra Script Sandbox Unauthorized Access Vulnerability [CVE-2019-8308]

CVE Number CVE-2019-8308

A vulnerability in Flatpak could allow a local attacker to gain escalated privileges on a targeted system.The vulnerability exists because the affected software improperly handles file descriptors related to /proc/self/exe. An attacker could exploit the vulnerability by persuading a user with root privileges to install a system-wide Flatpak application that has an apply_extra script, and then run the apply_extrascript in a sandbox with /proc mounted on the targeted system. A successful exploit could allow the attacker to escape sandbox protections and maliciously modify executable files as root on the host system.Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.Flatpak confirmed the vulnerability and released software updates.

Analysis

  • To exploit this vulnerability, an attacker may use misleading language or instructions to persuade a user on the targeted system to install a Flatpak application with an apply_extra script.

Safeguards

  • Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to have network access.Administrators are advised to use an unprivileged account when browsing the Internet.Administrators are advised to monitor critical systems.Users are advised not to open email messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in email messages are safe, they are advised not to open them.Users are advised not to visit websites or follow links that have suspicious characteristics or cannot be verified as safe.

Vendor Announcements

Fixed Software

  • Flatpak released software updates at the following links: Flatpak 1.0.7 and 1.2.3

Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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