Better control on user injected environment values#36132
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This commit includes two changes: * In `environment` we expanded the list of MacOS environment values which should be filtered. It was demonstrated that these can be used to get code execution in MacOS. * In `reexec` we no longer provide the cmdmsg.Environment for the `teleport exec`. As part of the development of a9055bc it was attempted to fully clear out the environment, but testing showed that to be potentially problematic. It was believed the safest option was to use the cmd environment, however this introduces a new source of environment variables. Because this exec happens under `root` this is particularly dangerous (even more so when combined with the missed OSX values mentioned above). As such we now are only providing the filtered exec environment, which is a closer (but safer) option to the functionality prior to a9055bc.
This was referenced Dec 29, 2023
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Public release of private fix: https://github.com/gravitational/teleport-private/pull/1218
PR fixes: https://github.com/gravitational/teleport-private/issues/1214
Will be disclosed under advisory: GHSA-vfxf-76hv-v4w4
This change expands the filtering done on environment variables so that possible code execution variables for macOS are excluded. Additionally the user provided values are removed from a point of execution done under
root.This PR expands this protection further by filtering all
DYLD_andLD_prefixed variables. However this change will not be backported and instead is planned to be a release as a behavior change in v15.changelog: macOS agent environment filtering documented under GHSA-vfxf-76hv-v4w4