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sudo -- arbitrary command execution


Tavis Ormandy reports:

The bash shell uses the value of the PS4 environment variable (after expansion) as a prefix for commands run in execution trace mode. Execution trace mode (xtrace) is normally set via bash's -x command line option or interactively by running "set -o xtrace". However, it may also be enabled by placing the string "xtrace" in the SHELLOPTS environment variable before bash is started.

A malicious user with sudo access to a shell script that uses bash can use this feature to run arbitrary commands for each line of the script.



portaudit: sudo -- arbitrary command execution

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Oliver Eikemeier <>