某安全网关前端JS分析

〇、前言

xxx是一款用于前端防御自动化工具的安全网关，核心代码由服务器下发给客户端执行，通过cookie将执行结果带回，再根据js获取的前端数据判断用户是否异常，完成安全检测

一、代码入口

js计算结果通过cookie传给服务器，参数名为：8PHkpr8y、JF7cGtR5、SflKxwRJ

经过调试分析，代码明文存放在ng_dynamic_defend文件中，核心逻辑位于尾部这几行

二、读取配置

get_global（）函数读取配置信息，放入_global_config中

window.config = 'eyJmaW5nZXIiOnsibmFtZSI6IkpGN2NHdFI1In0sImJvdCI6eyJlbmFibGVkIjp0cnVlLCJuYW1lIjoiOFBIa3ByOHkifSwic3VibWl0Ijp7ImVuYWJsZWQiOnRydWUsIm5hbWUiOiJVVmpES082biIsInVybCI6IiJ9LCJ0b2tlbiI6eyJlbmFibGVkIjp0cnVlLCJuYW1lIjoiU2ZsS3h3UkoiLCJ1cmwiOiJqc190ZXN0LmNvbTsiLCJpc19jaGVja191cmkiOnRydWUsImlzX2NoZWNrX2dldCI6dHJ1ZX0sImNvbnRlbnQiOnsiZW5hYmxlZCI6ZmFsc2UsIm5hbWUiOiJTZmxLeHdSSiIsImNvbmZ1c2VfdHlwZSI6IjAifSwic2NyaXB0Ijp7ImlzX2FudGlfZGVidWciOmZhbHNlfX0=';
!function (global) {
  function _base64_parse(e) {
    return CryptoJS.enc.Base64.parse(e).toString(CryptoJS.enc.Utf8)
  }

  function get_global() {
    var e = _base64_parse(global.config),
    t = JSON.parse(e);
    _global_config = global.nY1vq7Gi = t
  }
}(window);


/*
{
    "finger": {
        "name": "JF7cGtR5"
    },
    "bot": {
        "enabled": true,
        "name": "8PHkpr8y"
    },
    "submit": {
        "enabled": true,
        "name": "UVjDKO6n",
        "url": ""
    },
    "token": {
        "enabled": true,
        "name": "SflKxwRJ",
        "url": "js_test.com;",
        "is_check_uri": true,
        "is_check_get": true
    },
    "content": {
        "enabled": false,
        "name": "SflKxwRJ",
        "confuse_type": "0"
    },
    "script": {
        "is_anti_debug": false
    }
}
*/

三、数据采集

以下三个函数会使用到window对象来采集客户端数据：

get_tool_feature() 获得工具特征
get_browser_feature() 获得浏览器特征
get_fingerprint() 获得浏览器指纹

3.1 get_tool_feature()

get_webdriver()  //window.navigator.webdriver 
get_phantomjs()  //window.navigator.userAgent
get_bot()  //检测关键字：'__webdriver_evaluate','__selenium_evaluate','__webdriver_script_function','__webdriver_script_func','__webdriver_script_fn','__fxdriver_evaluate','__driver_unwrapped','__webdriver_unwrapped','__driver_evaluate','__selenium_unwrapped','__fxdriver_unwrapped''_phantom','__nightmare','_selenium','callPhantom','callSelenium','_Selenium_IDE_Recorder'
get_navigator_for_tool()  //window.navigator.languages
get_canvas_for_tool()  //window.document.createElement('canvas').getContext
get_storage_for_tool()  //window.localStorage && window.sessionStorage
get_consol()  //window.console.log(1)
get_awvs()  //检测关键字：'SimpleDOMXSSClass','MarvinHooks','MarvinPageExplorer','HashDOMXSSClass'
get_appscan()  //检测关键字：'appScanSendReplacement','appScanOnReadyStateChangeReplacement','appScanLoadHandler','appScanSetPageLoaded'

3.2 get_browser_feature()

get_indexedDB()  //window.indexedDB
get_openDatabase()  //window.openDatabase
get_localStorage()  //window.localStorage
get_sessionStorage()  //window.sessionStorage
get_audio()  //window.AudioContext.destination
get_file()  //'object' == typeof File || 'function' == typeof File
isCanvasSupported()  //window.document.createElement('canvas').getContext
isWebGlSupported()  //window.WebGLRenderingContext || window.document.createElement('canvas').getContext('webgl')
get_plugins()  //window.navigator.plugins
get_languages()  //window.navigator.languages
get_platform()  //window.navigator.platform
get_cpuClass()  //_navigator.cpuClass
get_hardwareConcurrency()  //_navigator.hardwareConcurrency
get_namespaces()  //window.document.namespaces
get_documentMode()  //window.document.documentMode
get_ActivexObject()  //window.document.ActivexObject
get_StyleMedia()  //window.StyleMedia
get_opera()  //window.opera
get_firefox()  //'undefined' != typeof InstallTrigger
get_chrome()  //window.chrome
get_safari()  ///constructor/i.test(window.HTMLElement) || '[object SafariRemoteNotification]' === (!window.safari || safari.pushNotification).toString()

3.3 get_fingerprint()

get_indexedDB()  //window.indexedDB
get_openDatabase()  //window.openDatabase
get_localStorage()  //window.localStorage
get_sessionStorage()  //window.sessionStorage
get_audio()  //window.AudioContext.destination
get_file()  //'object' == typeof File || 'function' == typeof File
get_canvas()  //window.document.createElement('canvas')
get_webgl()  //window..document.createElement('canvas').getContext('webgl')
get_webgl_render()  //window.document.createElement('canvas').getContext('webgl')
get_plugins()  //window.navigator.plugins
get_language()  //window.navigator.language || window.navigator.userLanguage || window.navigator.browserLanguage || window.navigator.systemLanguage ||
get_languages()  //window.navigator.languages
get_platform()  //window.navigator.platform
get_cpuClass()  //window.navigator.cpuClass
get_hardwareConcurrency()  //window.navigator.hardwareConcurrency
get_timezone_offset()  //(new Date).getTimezoneOffset()
get_timezone()  //window.Intl && window.Intl.DateTimeFormat
get_screen_ratio()  //window.screen.width / window.screen.height * 100
get_screen_resolution()  //window.screen.availHeight + 'X' + window.screen.availWidth + 'X' + window.screen.availLeft + 'X' + window.screen.availTop
get_touch_support()  //window.navigator.maxTouchPoints || window.navigator.msMaxTouchPoints
get_media_devices()  //window.navigator.mediaDevices && window.navigator.mediaDevices.enumerateDevices
get_battery()  //window.navigator.getBattery
get_adBlock()  //window.document.getElementsByClassName('adsbox') [0].offsetHeight
get_userAgent()  //window.navigator.userAgent

3.4 数据处理

set_bot_cookie()、set_fingerprint()两个函数分别将tool_feature、browser_feature与fingerprint加密写入到cokie中，变量名为：8PHkpr8y、JF7cGtR5

set_bot_cookie()

set_fingerprint()

四、事件监听

4.1 a标签

设置EventListenerEx()监听，当页面加载完成时触发load_func()，对当前cookie执行base64编码操作，并设置参数名为KBwtGA

function confuse_cookie() {
  var e;
  _document.cookie && 0 != _global_config.content.enabled && '1' == _global_config.content.confuse_type && (e = _document.cookie, clearAllCookie(), CookieUtil.set('KBwtGA', btoa(e)))
}

当发生点击事件时触发a_click_handler()，对请求地址添加令牌，变量名为SflKxwRJ

replace_url()调用get_token()生成加密tonken

4.2 form表单

设置EventListenerEx()监听，当发生表单事件时触发form_hook()，调用get_submit()对表单内数据加密，参数名为UVjDKO6n，调用get_token()生成加密tonken，参数名为SflKxwRJ

4.3 ajax请求

当发生ajax事件时触发ajax_hook()，对不同请求方式做了单独处理

监听到get请求时调用get_body_for_get()对args数据使用get_token()加密，监听到post请求时调用get_body_for_post()对请求体get_submit()加密、对url使用replace_url()调用get_token()生成加密tonken

五、总结

xxx的核心代码未经过加密或混淆以明文形式下发，格式化后通过调试分析比较容易弄清楚执行逻辑，代码主要实现以下两个功能：

采集window或者navigator的部分特征值，按位计算形成一个整数，再利用rc4算法加密，指纹特征存放在cookie中JF7cGtR5、工具特征存放在cookie中8PHkpr8y
设置a标签、form表单、ajax请求监听，触发时对数据内容调用get_submit()使用rc4算法加密、对url调用get_token()使用rc4算法计算token令牌