Azure WAF 403響應

Question

我在向我的 API 發送 PUT 請求時收到“403 ModSecurity 操作”。Gets 和 Posts 按預期工作。

我首先想到的是 WAF 可能會阻止特定的動詞（即 PUT），即“REQUEST-911-METHOD-ENFORCEMENT” 更多信息在這里

但隨后 .networking 團隊設法找到了請求的日志 -

TimeGenerated: 2018-05-04T09:55:42Z
    AzureDiagnostics    5/4/2018 10:55:42.000 AM    AzureDiagnostics    ApplicationGatewayFirewall  ApplicationGatewayFirewallLog   WAF-CPP-01  52.233.137.239  OWASP   3.0 200002  Blocked Global  Access denied with code 400 (phase 2). Match of "eq 0" against "REQBODY_ERROR" required.    JSON parsing error: parse error: invalid object key (must be a string)\x0a          cpp.api.cardiff.gov.uk  ApplicationGatewayRole_IN_0         

$table  AzureDiagnostics
TenantId    31c4d3f2-394f-4c06-833c-9d22912ec8ab
SourceSystem    Azure
TimeGenerated   2018-05-04T09:55:42Z
Type    AzureDiagnostics
ResourceId  /SUBSCRIPTIONS/ECA58BF3-DF5E-41E6-B113-BB96E1EBC768/RESOURCEGROUPS/RG-CPP-COREINFRASTRUCTURE/PROVIDERS/MICROSOFT.NETWORK/APPLICATIONGATEWAYS/WAF-CPP-01
OperationName   ApplicationGatewayFirewall
Category    ApplicationGatewayFirewallLog
Resource    WAF-CPP-01
ResourceGroup   RG-CPP-COREINFRASTRUCTURE
ResourceProvider    MICROSOFT.NETWORK
SubscriptionId  eca58bf3-df5e-41e6-b113-bb96e1ebc768
clientIp_s  52.233.137.239
ruleSetType_s   OWASP
ruleSetVersion_s    3.0
ruleId_s    200002
Message Mandatory rule. Cannot be disabled. Failed to parse request body.
action_s    Blocked
site_s  Global
details_message_s   Access denied with code 400 (phase 2). Match of "eq 0" against "REQBODY_ERROR" required.
details_data_s  JSON parsing error: parse error: invalid object key (must be a string)\x0a
hostname_s  cpp.api.cardiff.gov.uk
instanceId_s    ApplicationGatewayRole_IN_0
requestUri_s    /Notification/api/Notification/
ResourceType    APPLICATIONGATEWAYS
clientPort_d    0

    AzureDiagnostics    5/4/2018 10:55:42.000 AM    AzureDiagnostics    ApplicationGatewayAccess    ApplicationGatewayAccessLog WAF-CPP-01                                              ApplicationGatewayRole_IN_0 52.233.137.239  PUT 

$table  AzureDiagnostics
TenantId    31c4d3f2-394f-4c06-833c-9d22912ec8ab
SourceSystem    Azure
TimeGenerated   2018-05-04T09:55:42Z
Type    AzureDiagnostics
ResourceId  /SUBSCRIPTIONS/ECA58BF3-DF5E-41E6-B113-BB96E1EBC768/RESOURCEGROUPS/RG-CPP-COREINFRASTRUCTURE/PROVIDERS/MICROSOFT.NETWORK/APPLICATIONGATEWAYS/WAF-CPP-01
OperationName   ApplicationGatewayAccess
Category    ApplicationGatewayAccessLog
Resource    WAF-CPP-01
ResourceGroup   RG-CPP-COREINFRASTRUCTURE
ResourceProvider    MICROSOFT.NETWORK
SubscriptionId  eca58bf3-df5e-41e6-b113-bb96e1ebc768
instanceId_s    ApplicationGatewayRole_IN_0
clientIP_s  52.233.137.239
httpMethod_s    PUT
requestUri_s    /Notification/api/Notification/
requestQuery_s  -
userAgent_s PostmanRuntime/7.1.1
httpVersion_s   HTTP/1.1
sslEnabled_s    on
host_s  cpp.api.cardiff.gov.uk
ResourceType    APPLICATIONGATEWAYS
clientPort_d    1,025
httpStatus_d    400
receivedBytes_d 1,360
sentBytes_d 185
timeTaken_d 56

錯誤提到請求正文有錯誤，JSON 不正確。 但我的結局似乎一切都很好：/

我已經通過 swagger 和 postman 進行了測試。

Answer 1

我們的 WAF 剛剛遇到了這個確切的問題。 問題不是 JSON 格式不正確，而是它太大了。 我一直無法找到關於什么構成大型 JSON 有效負載的確切數字，但如果請求的內容長度超過大約 120-150kb，它就會發生。

Answer 2

我遇到了同樣的問題，結果證明這是應用程序網關 WAF 策略中的一個限制，它只允許它檢查大小小於 128 kB 的請求主體。

對我來說，基礎設施在 Azure 中，顯然應用程序網關的版本升級將允許檢查（和解析）多達 2 MB 的主體。

對於 Azure 中的應用程序網關，主體大小限制記錄在此處： https://learn.microsoft.com/en-us/azure/web-application-firewall/ag/application-gateway-waf-request-size-limits#limits