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VPC Flow Logs

Overview

Amazon VPC Flow Logs is a feature that provides the ability to capture information about IP network traffic as it enters or exits from network interface in your Amazon VPC (Amazon Virtual Private Cloud). VPC Flow Logs can help you with a number of tasks, such as:

  • Diagnosing overly restrictive security group rules
  • Monitoring the traffic that is reaching your instance
  • Determining the direction of the traffic to and from the network interfaces

Benefit from SEKOIA.IO built-in rules and upgrade AWS VPC Flow Logs with the following detection capabilities out-of-the-box.

SEKOIA.IO x AWS VPC Flow Logs on ATT&CK Navigator

SEKOIA.IO Intelligence Feed

Detect threats based on indicators of compromise (IOCs) collected by SEKOIA's Threat and Detection Research team.

  • Effort: elementary

Event Categories

The following table lists the data source offered by this integration.

Data Source Description
Host network interface every packets passing through the AWS account are logged
Netflow/Enclave netflow AWS Flow Logs are Netflow-like
Network device logs packets logged by Flow Logs
Network protocol analysis traffic analysis at levels 2/3/4

In details, the following table denotes the type of events produced by this integration.

Name Values
Kind event
Category ["network"]
Type ``

Event Samples

Find below few samples of events and how they are normalized by Sekoia.io.

{
    "message": "2 424805057484 eni-0f06a40fc9be596f6 212.83.179.156 10.0.0.96 123 123 17 2 152 1599665193 1599665488 ACCEPT OK",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2020-09-09T15:26:33Z",
        "end": "2020-09-09T15:31:28Z",
        "action": "accept",
        "type": [
            "allowed"
        ]
    },
    "action": {
        "outcome": "ok",
        "type": "forward",
        "name": "accept",
        "target": "network-traffic"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "424805057484"
        }
    },
    "destination": {
        "port": 123,
        "ip": "10.0.0.96",
        "address": "10.0.0.96"
    },
    "network": {
        "iana_number": "17",
        "transport": "udp"
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-0f06a40fc9be596f6"
            }
        }
    },
    "source": {
        "port": 123,
        "bytes": 152,
        "packets": 2,
        "ip": "212.83.179.156",
        "address": "212.83.179.156"
    },
    "user": {
        "id": "424805057484"
    },
    "@timestamp": "2020-09-09T15:26:33Z",
    "related": {
        "ip": [
            "10.0.0.96",
            "212.83.179.156"
        ]
    }
}

{
    "message": "{\"version\":2,\"account_id\":\"424805057484\",\"interface_id\":\"eni-0f06a40fc9be596f6\",\"srcaddr\":\"5.6.7.8\",\"dstaddr\":\"1.2.3.4\",\"srcport\":4712,\"dstport\":53205,\"protocol\":6,\"packets\":12,\"bytes\":2610,\"start\":1661950735,\"end\":1661950746,\"action\":\"ACCEPT\",\"log_status\":\"OK\"}\n",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2022-08-31T12:58:55Z",
        "end": "2022-08-31T12:59:06Z",
        "action": "accept",
        "type": [
            "allowed"
        ]
    },
    "action": {
        "outcome": "ok",
        "type": "forward",
        "name": "accept",
        "target": "network-traffic"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "424805057484"
        }
    },
    "destination": {
        "port": 53205,
        "ip": "1.2.3.4",
        "address": "1.2.3.4"
    },
    "network": {
        "iana_number": "6",
        "transport": "tcp"
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-0f06a40fc9be596f6"
            }
        }
    },
    "source": {
        "port": 4712,
        "bytes": 2610,
        "packets": 12,
        "ip": "5.6.7.8",
        "address": "5.6.7.8"
    },
    "user": {
        "id": "424805057484"
    },
    "@timestamp": "2022-08-31T12:58:55Z",
    "related": {
        "ip": [
            "1.2.3.4",
            "5.6.7.8"
        ]
    }
}

{
    "message": "5 424805057484 eni-1235b8ca123456789 52.95.128.179 10.0.0.71 46945 53 17 1 73 1658131186 1658131216 ACCEPT OK vpc-abcdefab012345678 subnet-aaaaaaaa012345678 - 0 IPv4 52.95.128.179 10.0.0.71 eu-west-1 euw1-az3 - - - - egress 8",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2022-07-18T07:59:46Z",
        "end": "2022-07-18T08:00:16Z",
        "action": "accept",
        "type": [
            "allowed"
        ]
    },
    "action": {
        "outcome": "ok",
        "type": "forward",
        "name": "accept",
        "target": "network-traffic"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "424805057484"
        }
    },
    "destination": {
        "port": 53,
        "ip": "10.0.0.71",
        "address": "10.0.0.71"
    },
    "network": {
        "iana_number": "17",
        "transport": "udp"
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-1235b8ca123456789"
            }
        }
    },
    "source": {
        "port": 46945,
        "bytes": 73,
        "packets": 1,
        "ip": "52.95.128.179",
        "address": "52.95.128.179"
    },
    "user": {
        "id": "424805057484"
    },
    "@timestamp": "2022-07-18T07:59:46Z",
    "related": {
        "ip": [
            "10.0.0.71",
            "52.95.128.179"
        ]
    }
}

{
    "message": "2 123456789010 eni-1235b8ca123456789 2001:db8:1234:a100:8d6e:3477:df66:f105 2001:db8:1234:a102:3304:8879:34cf:4071 34892 22 6 54 8855 1477913708 1477913820 ACCEPT OK",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2016-10-31T11:35:08Z",
        "end": "2016-10-31T11:37:00Z",
        "action": "accept",
        "type": [
            "allowed"
        ]
    },
    "action": {
        "outcome": "ok",
        "type": "forward",
        "name": "accept",
        "target": "network-traffic"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "123456789010"
        }
    },
    "destination": {
        "port": 22,
        "ip": "2001:db8:1234:a102:3304:8879:34cf:4071",
        "address": "2001:db8:1234:a102:3304:8879:34cf:4071"
    },
    "network": {
        "iana_number": "6",
        "transport": "tcp"
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-1235b8ca123456789"
            }
        }
    },
    "source": {
        "port": 34892,
        "bytes": 8855,
        "packets": 54,
        "ip": "2001:db8:1234:a100:8d6e:3477:df66:f105",
        "address": "2001:db8:1234:a100:8d6e:3477:df66:f105"
    },
    "user": {
        "id": "123456789010"
    },
    "@timestamp": "2016-10-31T11:35:08Z",
    "related": {
        "ip": [
            "2001:db8:1234:a100:8d6e:3477:df66:f105",
            "2001:db8:1234:a102:3304:8879:34cf:4071"
        ]
    }
}

{
    "message": "2 123456789010 eni-1235b8ca123456789 - - - - - - - 1431280876 1431280934 - NODATA",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2015-05-10T18:01:16Z",
        "end": "2015-05-10T18:02:14Z"
    },
    "action": {
        "outcome": "nodata",
        "type": "forward"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "123456789010"
        }
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-1235b8ca123456789"
            }
        }
    },
    "user": {
        "id": "123456789010"
    },
    "@timestamp": "2015-05-10T18:01:16Z"
}

{
    "message": "2 424805057484 eni-0f06a40fc9be596f6 195.14.170.50 10.0.0.96 53996 20248 6 1 40 1599665374 1599665428 REJECT OK",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2020-09-09T15:29:34Z",
        "end": "2020-09-09T15:30:28Z",
        "action": "reject",
        "type": [
            "denied"
        ]
    },
    "action": {
        "outcome": "ok",
        "type": "forward",
        "name": "reject",
        "target": "network-traffic"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "424805057484"
        }
    },
    "destination": {
        "port": 20248,
        "ip": "10.0.0.96",
        "address": "10.0.0.96"
    },
    "network": {
        "iana_number": "6",
        "transport": "tcp"
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-0f06a40fc9be596f6"
            }
        }
    },
    "source": {
        "port": 53996,
        "bytes": 40,
        "packets": 1,
        "ip": "195.14.170.50",
        "address": "195.14.170.50"
    },
    "user": {
        "id": "424805057484"
    },
    "@timestamp": "2020-09-09T15:29:34Z",
    "related": {
        "ip": [
            "10.0.0.96",
            "195.14.170.50"
        ]
    }
}

{
    "message": "{\"version\":2,\"account_id\":\"424805057484\",\"interface_id\":\"eni-0f06a40fc9be596f6\",\"srcaddr\":\"1.2.3.4\",\"dstaddr\":\"5.6.7.8\",\"srcport\":53094,\"dstport\":2323,\"protocol\":6,\"packets\":1,\"bytes\":40,\"start\":1661950735,\"end\":1661950746,\"action\":\"REJECT\",\"log_status\":\"OK\"}\n",
    "event": {
        "kind": "event",
        "category": [
            "network"
        ],
        "start": "2022-08-31T12:58:55Z",
        "end": "2022-08-31T12:59:06Z",
        "action": "reject",
        "type": [
            "denied"
        ]
    },
    "action": {
        "outcome": "ok",
        "type": "forward",
        "name": "reject",
        "target": "network-traffic"
    },
    "cloud": {
        "provider": "aws",
        "service": {
            "name": "vpc"
        },
        "account": {
            "id": "424805057484"
        }
    },
    "destination": {
        "port": 2323,
        "ip": "5.6.7.8",
        "address": "5.6.7.8"
    },
    "network": {
        "iana_number": "6",
        "transport": "tcp"
    },
    "observer": {
        "ingress": {
            "interface": {
                "name": "eni-0f06a40fc9be596f6"
            }
        }
    },
    "source": {
        "port": 53094,
        "bytes": 40,
        "packets": 1,
        "ip": "1.2.3.4",
        "address": "1.2.3.4"
    },
    "user": {
        "id": "424805057484"
    },
    "@timestamp": "2022-08-31T12:58:55Z",
    "related": {
        "ip": [
            "1.2.3.4",
            "5.6.7.8"
        ]
    }
}

Extracted Fields

The following table lists the fields that are extracted, normalized under the ECS format, analyzed and indexed by the parser. It should be noted that infered fields are not listed.

Name Type Description
@timestamp date Date/time when the event originated.
action.name keyword The name of the action
action.outcome keyword The outcome of the action
action.target keyword The target of the action
action.type keyword The type of the action
cloud.account.id keyword The cloud account or organization id.
cloud.provider keyword Name of the cloud provider.
cloud.service.name keyword The cloud service name.
destination.ip ip IP address of the destination.
destination.port long Port of the destination.
event.action keyword The action captured by the event.
event.category keyword Event category. The second categorization field in the hierarchy.
event.end date event.end contains the date when the event ended or when the activity was last observed.
event.kind keyword The kind of the event. The highest categorization field in the hierarchy.
event.start date event.start contains the date when the event started or when the activity was first observed.
network.iana_number keyword IANA Protocol Number.
observer.ingress.interface.name keyword Interface name
source.bytes long Bytes sent from the source to the destination.
source.ip ip IP address of the source.
source.packets long Packets sent from the source to the destination.
source.port long Port of the source.
user.id keyword Unique identifier of the user.

Configure

VPC Flow Logs

As a prerequisite, you need an existing VPC, subnet or network interface (Elastic Load Balancing, Amazon RDS, Amazon ElastiCache, Amazon Redshift, Amazon WorkSpaces, NAT gateways, Transit gateways) to create a flow log. If you create a flow log for a subnet or VPC, each network interface in that subnet or VPC is monitored.

In the AWS console, navigate to: Services > VPC. From there, select the resource for which you want to capture information. The flow logs are available on the following resources: VPC, subnet, or network interfaces.

For VPC and subnet:

  • Select the specific resource to monitor
  • Go to the tab Flow logs
  • Click on Create flow log
  • Set up the flow log: we recommend to capture all traffic (accepted and rejected).

Prerequisites

  • An administator access to the Amazon console with the permission to create SQS queue and S3 notifications.
  • A self managed AWS S3 bucket where events will be published prior to be consumed by Sekoia.io.

Create a SQS queue

This integration relies on S3 Event Notifications (SQS) to discover new S3 objects.

To enable the S3 Event Notification:

  1. Create a queue in the SQS service by following this guide
  2. In the Access Policy step, choose the advanced configuration and adapt this configuration sample with your own SQS Amazon Resource Name (ARN) (the main change is the Service directive allowing S3 bucket access): 
    {
  "Version": "2008-10-17",
  "Id": "__default_policy_ID",
  "Statement": [
    {
      "Sid": "__owner_statement",
      "Effect": "Allow",
      "Principal": {
        "Service": "s3.amazonaws.com"
      },
      "Action": "SQS:*",
      "Resource": "arn:aws:sqs:XXX:XXX"
    }
  ]
}

Note

Keep in mind that you have to create the SQS queue in the same region as the S3 bucket you want to watch.

Create a S3 Event Notification

Use the following guide to create S3 Event Notification and then:

  1. Select the notification for object creation in the Event type section
  2. As the destination, choose the SQS service
  3. Select the queue you created in the previous section

Create the intake

Go to the intake page and create a new intake from the format AWS Flowlogs.

Pull events

To start to pull events, you have to:

  1. Go to the playbook page and create a new playbook with the AWS Fetch new logs on S3 connector.
  2. Set up the module configuration with the AWS Access Key, the secret key and the region name. Set up the trigger configuration with the name of the SQS queue and the intake key, from the intake previously created.
  3. Start the playbook and enjoy your events.

Further Readings