關於超星學習通視頻加密分析

本文轉載自查看原文 2020-05-04 12:20 1522 爬蟲從入門到入獄

學校又有新的課程要觀看了,沒辦法,只能上才藝了

對於像這種網課類的觀看,發送的數據請求一般都是ajax,攜帶的關鍵參數大致如下

當前的觀看時間
當前觀看的課程章節id
當前課程的id

隨便找了一個課程,發送的數據如下

因為我已經分析過了,就直接告訴大家,發送數據的參數只有enc是不斷變化的,且用js加密生成,objectid和ontherinfo針對當前所看的課程章節是不變的,
觀看其他的課程就會發生相對的變化,好了,通過單詞的字面意思大致知道意思,接下來我們就要分析enc是怎么生成的,好模擬發送對應的請求

找js的方法有很多,這里就不介紹了,網上一大堆方法,我這里通過發送對應的ajax的initiator找到了相關的js文件

我這里為了方便觀看,直接提取出關鍵的js代碼

var format = "[{0}][{1}][{2}][{3}][{4}][{5}][{6}][{7}]"
var clipTime = (params.startTime || "0") + "_" + (params.endTime || params.duration);
var enc = Ext.String.format(format, params.clazzId, params.userid, params.jobid ? params.jobid : "", params.objectId, currentTimeSec * 1000, "d_yHJ!$pdA~5", params.duration * 1000, clipTime);
var rurl = [params.reportUrl, "/", params.dtoken, "?clazzId=", params.clazzId, "&playingTime=", currentTimeSec, "&duration=", params.duration, "&clipTime=", clipTime, "&objectId=", params.objectId, "&otherInfo=", params.otherInfo, "&jobid=", params.jobid, "&userid=", params.userid, "&isdrag=", isdrag, "&view=pc", "&enc=", md5(enc), "&rt=", params.rt, "&dtype=Audio", "&_t=", new Date().getTime()].join("");

為了更方便的觀看數據,我已經提前打好了斷點,拿到了數據,可以看到enc其實是拿對應的參數進行字符串的拼接,然后做md5簽名
我們已經知道了enc是怎么生成的,然后我們需要知道其他的參數怎么來的,前面已經說過,既然這些參數是不變的,那么一般都會在頁面剛加載的時候就已經生成了
我們對其中任一一個固定的值進行全文檢索

 mArg = {"attachments":[{"headOffset":139000,"jobid":"1581681271463334","otherInfo":"nodeId_305814262-cpi_67960467","isPassed":false,"property":{"jobid":"1581681271463334","switchwindow":"true","size":1025113278,"fastforward":"true","hsize":"977.62 MB","module":"insertvideo","name":"3.5 從“全面建設小康”到“全面建成小康”.mp4","mid":"9733390305491581681270487","type":".mp4","objectid":"9c3a5a79e7d0473b06409f9bb566acad","_jobid":"1581681271463334"},"mid":"9733390305491581681270487","playTime":139000,"job":true,"type":"video","objectId":"9c3a5a79e7d0473b06409f9bb566acad"}],"defaults":{"fid":"1982","isFiled":0,"ignoreVideoCtrl":0,"reportUrl":"https://mooc1-1.chaoxing.com/multimedia/log/a/67960467","userid":"82506971","reportTimeInterval":60,"initdataUrl":"https://mooc1-1.chaoxing.com/richvideo/initdatawithviewer","knowledgeid":305814262,"qnenc":"4d74ade22640d3418796027099215e30","defenc":"9e694cf3bbb44d0d9764fa88acfb3dd5","clazzId":25967418,"cardid":274708987,"imageUrl":"https://p.ananas.chaoxing.com/star3/origin/3a7c4e2929905646967168696f78ff01.png","lastmodifytime":1588505782000,"state":0,"courseid":211852763,"subtitleUrl":"https://mooc1-1.chaoxing.com/richvideo/subtitle"},"control":true};