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GHSA-33qf-q99x-wpm8
No affected components available
Impact
Up to 1.0.0 of home-assitant-cli (or hass-cli for short) an unrestricted environment was used to handle Jninja2 templates instead of a sandboxed one. The user-supplied input within Jinja2 templates was rendered locally with no restrictions. This gave users access to Python's internals and extended the scope of templating beyond the intended usage.
E. g., it was possible to render a template with hass-cli template bad-template.j2 --local that contained entries like
{%- set b = environ.__globals__['__builtins__'] -%}
{%- set os = b['__import__']('os') -%}
{%- set bio = b['__import__']('builtins') -%}
...
or other malicious Jinja2 expressions. This can lead to arbitrary code execution on the local machine.
In a two step process an adversary could trick/convince an user to download third-party templates which contain harmful code (e. g., perform data manipulation or establish a remote shell) then to render those templates unchecked/reviewed/verified with --local.
The issue only affect the local machine and not a remote Home Assistant instance. It also requires user interventions.
Patches
1.0.0 uses ImmutableSandboxedEnvironment and restricts the usage of environment variables.
Workarounds
Evaluate the Jninja2 templates manually or tool-based before rendering with hass-cli.
The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs high-level or administrative privileges. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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