There are many grep flavors that in many cases are just copies, symlinks or wrappers around the original binary that may share the same behavior, for example: egrep, fgrep, zgrep, etc.
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
grep '' $LFILEIt 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 grep) .; chmod +s ./grep'
LFILE=file_to_read
./grep '' $LFILEIt 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 grep '' $LFILE