CVE-2021-0256 Explained : Impact and Mitigation
Learn about CVE-2021-0256, a local privilege escalation vulnerability in Juniper Networks Junos OS due to the mosquitto message broker. Find out the impact, affected systems, exploitation details, and mitigation steps.
A sensitive information disclosure vulnerability in the mosquitto message broker of Juniper Networks Junos OS may allow a locally authenticated user with shell access the ability to read portions of sensitive files, such as the master.passwd file. This vulnerability affects various versions of Junos OS, allowing a local privileged user to access sensitive information stored on the local filesystem.
Understanding CVE-2021-0256
This CVE discloses a local privilege escalation vulnerability in Juniper Networks Junos OS due to the mosquitto message broker implementation.
What is CVE-2021-0256?
The vulnerability in the mosquitto message broker of Juniper Networks Junos OS allows a local authenticated user to access sensitive information like the master.passwd file, potentially leading to unauthorized access.
The Impact of CVE-2021-0256
This vulnerability could be exploited by a local privileged user to run mosquitto with root privileges and access sensitive data.
Technical Details of CVE-2021-0256
The following are the key technical details associated with CVE-2021-0256:
Vulnerability Description
The vulnerability allows a locally authenticated user to read sensitive files due to the setuid permissions of the mosquitto message broker.
Affected Systems and Versions
Juniper Networks Junos OS versions 17.3 to 20.2 are affected by this vulnerability, with specific versions listed as vulnerable.
Exploitation Mechanism
The exploitation of this vulnerability requires shell access by a local authenticated user to potentially escalate privileges and access sensitive information.
Mitigation and Prevention
To mitigate the risks associated with CVE-2021-0256, consider the following measures:
Immediate Steps to Take
Implement access lists and firewall filters to restrict device access to trusted hosts. Limit shell access to authorized system administrators.
Long-Term Security Practices
Regularly update Junos OS to the patched versions provided by Juniper Networks to prevent exploitation of this vulnerability.
Patching and Updates
Ensure that your Junos OS is updated to the following versions or later: 17.3R3-S12, 17.4R3-S4, 18.1R3-S12, 19.1R3-S4, 19.3R3-S1, 19.3R3-S2, 19.4R2-S3, 20.1R2, 20.2R1-S3, 20.2R2, 20.2R3, and 20.3R1.