[ Hackerslab bug_paper ] Linux dump buffer overflow


File   :   /sbin/dump

SYSTEM :   Linux


INFO :


The problem occurs when it gets the argument.
It accepts the argument without checking out its length, and this causes =
the problem.

It seems that this vulnerability also applies to RedHat Linux 6.2beta,
the latest version.


[loveyou@loveyou SOURCES]$ dump  -f a `perl -e 'print "x" x 556'`
  DUMP: Date of this level 0 dump: Mon Feb 28 14:45:01 2000
  DUMP: Date of last level  dump: the epoch
  DUMP: Dumping xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx to a
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx=
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: =C6=C4=C0=CF =C0=CC=B8=
=A7=C0=CC =B3=CA=B9=AB =B1=E9=B4=CF=B4=D9 while opening filesystem
  DUMP: SIGSEGV: ABORTING!
Segmentation fault

[loveyou@loveyou SOURCES]$ dump  -f a `perl -e 'print "loveyou" x 556'`
  DUMP: SIGSEGV: ABORTING!
Segmentation fault    <=3D  occur ctime4()


How to fix
----------

patch :

[root@loveyou SOURCES]# diff -ru dump-0.4b13/dump/main_orig.c dump-0.4b13=
/dump/main.c
--- dump-0.4b13/dump/main_orig.c        Mon Feb 28 14:40:01 2000
+++ dump-0.4b13/dump/main.c     Mon Feb 28 14:40:57 2000
@@ -273,6 +273,9 @@
                exit(X_STARTUP);
        }
        disk =3D *argv++;
+        if ( strlen(disk) > 255 )
+           exit(X_STARTUP);
+
        argc--;
        if (argc >=3D 1) {
                (void)fprintf(stderr, "Unknown arguments to dump:");



hot fix :
it  is recommended that  the suid bit is
removed from dump using command :

    chmod a-s /sbin/dump




- Yong-jun, Kim -
e - mail : loveyou@hackerslab.org       s96192@ce.hannam.ac.kr
homepage : http://www.hackerslab.org    http://ce.hannam.ac.kr/~s96192