Rules: HTTP Response Error Spike - External
HTTP web services provide response codes to client requests. The response code numbers in the 400s are used to indicate a client related error and response code numbers in the 500s represent server related errors. This rule looks for a web client receiving a large frequency of web errors within a short period of time. It is unusual for a web client to cause this many errors in a short period of time. Common occurrences for this behavior is scanning/probing activity or scripted web clients which are now encountering errors due to a misconfiguration or recent change. This rule alerts when a host external to the monitored network triggers the threshold.
| Detail | Value |
|---|---|
| Type | Threshold |
| Category | Discovery |
| Apply Risk to Entities | device_ip, srcDevice_ip, dstDevice_ip, device_hostname, srcDevice_hostname, dstDevice_hostname |
| Signal Name | HTTP Response Error Spike - External |
| Summary Expression | High number of external HTTP response errors from IP: {{srcDevice_ip}} to {{dstDevice_ip}} |
| Threshold Count | 350 |
| Threshold Window | 5m |
| Score/Severity | Static: 2 |
| Enabled by Default | True |
| Prototype | False |
| Tags | _mitreAttackTactic:TA0007, _mitreAttackTactic:TA0011, _mitreAttackTactic:TA0043, _mitreAttackTechnique:T1595, _mitreAttackTechnique:T1190, _mitreAttackTechnique:T1595.001, _mitreAttackTechnique:T1595.002, _mitreAttackTactic:TA0009, _mitreAttackTechnique:T1213, _mitreAttackTechnique:T1213.001 |
- Amazon AWS - Application Load Balancer
- Amazon AWS - Elastic Load Balancer
- Bro - Bro
- Cloudflare - Logpush
- Microsoft - Azure
- Microsoft - IIS
- Zscaler - Nanolog Streaming Service
| Origin | Field |
|---|---|
| Normalized Schema | device_hostname |
| Normalized Schema | device_ip |
| Normalized Schema | dstDevice_hostname |
| Normalized Schema | dstDevice_ip |
| Normalized Schema | dstDevice_ip_isInternal |
| Normalized Schema | http_response_statusCode |
| Normalized Schema | srcDevice_hostname |
| Normalized Schema | srcDevice_ip |
| Normalized Schema | srcDevice_ip_isInternal |