.. / xxd

Star

• File write
• File read
• SUID
• Sudo

File write

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

• LFILE=file_to_write
  echo DATA | xxd | xxd -r - "$LFILE"

File read

It reads data from files, it may be used to do privileged reads or disclose files outside a restricted file system.

• LFILE=file_to_read
  xxd "$LFILE" | xxd -r

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 xxd) .; chmod +s ./xxd'
  
  LFILE=file_to_read
  ./xxd "$LFILE" | xxd -r

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_read
  sudo xxd "$LFILE" | xxd -r