GHSA-6fgx-x7m2-74qm: tracexec has `env` command argument injection via environment variables starting with dash in traced exec events

Impact

For tracexec’s command line reconstruction feature, when a traced process executes another process with a environment variable where the key starts with a dash, tracexec incorrectly shows its commandline where such environment variables could cause argument injection for the env command.
Such an injection is completely at the UI level unless the user tries to copy the command line with the injection and paste it into a terminal to execute it.

A minimal POC is executing env – -a=b bash --norc in tracexec’s TUI mode. The resulting command line of env executing bash would be env -a bash -a=b _=/usr/bin/env /usr/bin/bash --norc in tracexec’s TUI, which injects -a=b into env’s arguments.

This has very limited effect for security. A local adversarial could leverage this to make tracexec show an inaccurate reconstructed commandline for their executed command. If the user of tracexec decides to copy and run the reconstructed commandline,
there could be injection for env’s --block-signal, --default-signal, --ignore-signal, --split-string, --unset, --chdir, --argv0 arguments.

Patches

The fix is kxxt/tracexec#118. Users are advised to upgrade to 0.14.0.

Workarounds

Don’t blindly paste and execute commands copied from tracexec that contains environment variable where the key starts with a dash.

References

• GHSA-6fgx-x7m2-74qm
• kxxt/tracexec#118
• kxxt/tracexec@0dbe632