Java中的JSON注入强化错误

Question

我从客户端获取 SUBSCRIPTION_JSON ，将其转换为String，然后使用gson库将其设置为Model
Object。在Fortify安全性上运行代码时，它在以下代码上给我Json注入错误，并显示以下消息：

这是错误：

On line 159 of ActionHelper.java, the method jsonToObject() writes unvalidated input into JSON. This call could allow an attacker to inject arbitrary elements or attributes into the JSON entity.The method writes unvalidated input into JSON. This call could allow an attacker to inject arbitrary elements or attributes into the JSON entity.

Explanation
JSON injection occurs when:

1. Data enters a program from an untrusted source.

In this case the data enters at getString() in **SubscriptionAction.java** at line 355.


2. The data is written to a JSON stream.

In this case the JSON is written by fromJson() in **ActionHelper.java** at line 159.

SubscriptionAction.java

final String subscriptionJson = subscriptionForm.getString(SUBSCRIPTION_JSON);

ActionHelper.java

public static <T> T jsonToObject(final String jsonString, final Class<T> className) {
        T object = null;
        if (StringUtils.isNotBlank(jsonString)) {
            final Gson gson = (Gson) BeanLocator.getInstance().getBean(GSON);
            object = gson.fromJson(jsonString, className);
        }
        return object;
    }

SUBSCRIPTION_JSON- >

{
    "subscriptions": [{
        "attributeId": "1",
        "items": [{
            "strId": "ALL",
            "nodeType": "G"
        }, {
            "strId": "VO_ENTRY_TIMING_DELAY",
            "nodeType": "L"
        }, {
            "strId": "O_INVALID",
            "nodeType": "L"
        }, {
            "strId": "O_LINE_INVALID",
            "nodeType": "L"
        }, {
            "strId": "V_INVALID",
            "nodeType": "L"
        }, {
            "strId": "V_ADDRESS_INVALID",
            "nodeType": "L"
        }]
    }, {
        "attributeId": "2001",
        "items": [{
            "strId": "OSTBU",
            "nodeType": "L"
        }]
    }]
}

Answer 1

在将其设置为Model
Object之前，您必须验证接收到的json以确保它准确包含预期的内容。例如，您可以实现一个验证器，该验证器使用所需的字段/格式模式检查json。