/
dns.go
221 lines (205 loc) · 6.73 KB
/
dns.go
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package zeek
import (
"fmt"
"strconv"
"strings"
"time"
"github.com/activecm/espy/espy/input"
"github.com/activecm/espy/espy/util"
)
func dnsQueryTypeToID(qType string) (string, error) {
//definitions based on https://github.com/miekg/dns/blob/master/types.go
dnsMap := map[string]string{
"A": "1",
"NS": "2",
"MD": "3",
"MF": "4",
"CNAME": "5",
"SOA": "6",
"MB": "7",
"MG": "8",
"MR": "9",
"NULL": "10",
"PTR": "12",
"HINFO": "13",
"MINFO": "14",
"MX": "15",
"TXT": "16",
"RP": "17",
"AFSDB": "18",
"X25": "19",
"ISDN": "20",
"RT": "21",
"NSAPPTR": "23",
"SIG": "24",
"KEY": "25",
"PX": "26",
"GPOS": "27",
"AAAA": "28",
"LOC": "29",
"NXT": "30",
"EID": "31",
"NIMLOC": "32",
"SRV": "33",
"ATMA": "34",
"NAPTR": "35",
"KX": "36",
"CERT": "37",
"DNAME": "39",
"OPT": "41",
"APL": "42",
"DS": "43",
"SSHFP": "44",
"RRSIG": "46",
"NSEC": "47",
"DNSKEY": "48",
"DHCID": "49",
"NSEC3": "50",
"NSEC3PARAM": "51",
"TLSA": "52",
"SMIMEA": "53",
"HIP": "55",
"NINFO": "56",
"RKEY": "57",
"TALINK": "58",
"CDS": "59",
"CDNSKEY": "60",
"OPENPGPKEY": "61",
"CSYNC": "62",
"ZONEMD": "63",
"SVCB": "64",
"HTTPS": "65",
"SPF": "99",
"UINFO": "100",
"UID": "101",
"GID": "102",
"UNSPEC": "103",
"NID": "104",
"L32": "105",
"L64": "106",
"LP": "107",
"EUI48": "108",
"EUI64": "109",
"URI": "256",
"CAA": "257",
"AVC": "258",
}
qTypeID, ok := dnsMap[qType]
if !ok {
return "", fmt.Errorf("invalid DNS type: %s", qType)
}
return qTypeID, nil
}
type DnsTSV struct{}
func (c DnsTSV) Header() TSVHeader {
return TSVHeader{
Separator: "\\x09",
SetSeparator: ",",
EmptyField: "(empty)",
UnsetField: "-",
Path: "dns",
Fields: []string{
"ts", "uid", "id.orig_h", "id.orig_p", "id.resp_h", "id.resp_p",
"proto", "trans_id", "rtt", "query", "qclass", "qclass_name",
"qtype", "qtype_name", "rcode", "rcode_name", "AA", "TC", "RD", "RA", "Z",
"answers", "TTLs", "rejected", "agent_hostname", "agent_uuid",
},
Types: []string{
"time", "string", "addr", "port", "addr", "port", "enum", "count",
"interval", "string", "count", "string", "count", "string", "count", "string",
"bool", "bool", "bool", "bool", "count", "vector[string]", "vector[interval]",
"bool", "string", "string",
},
}
}
func (c DnsTSV) FormatLines(outputData []input.ECSRecord) (output string, err error) {
var outputBuilder strings.Builder
header := c.Header()
//escape \\x09 to tab
separator, _ := strconv.Unquote(fmt.Sprintf("\"%s\"", header.Separator))
for i := range outputData {
goStartTime, err := time.Parse(time.RFC3339Nano, outputData[i].RFCTimestamp)
if err != nil {
return output, input.ErrMalformedECSRecord
}
answersSetBuilder := strings.Builder{}
answerTypeName := header.UnsetField
answerTypeID := header.UnsetField
// Don't report CNAME responses since Zeek doesn't
// WEIRD: Windows issues A queries for IP addresses and gets back "-" in the answers
shouldHandleAnswer := func(dnsType, dnsData string) bool {
return dnsType != "CNAME" && dnsData != "-"
}
if len(outputData[i].DNS.Answers) > 0 {
// We have to split out the last iteration of this loop so we don't write out a trailing comma
for j := 0; j < len(outputData[i].DNS.Answers)-1; j++ {
if shouldHandleAnswer(outputData[i].DNS.Answers[j].Type, outputData[i].DNS.Answers[j].Data) {
answersSetBuilder.WriteString(outputData[i].DNS.Answers[j].Data)
answersSetBuilder.WriteString(header.SetSeparator)
answerTypeName = outputData[i].DNS.Answers[j].Type
}
}
lastIdx := len(outputData[i].DNS.Answers) - 1
if shouldHandleAnswer(outputData[i].DNS.Answers[lastIdx].Type, outputData[i].DNS.Answers[lastIdx].Data) {
answersSetBuilder.WriteString(outputData[i].DNS.Answers[lastIdx].Data)
answerTypeName = outputData[i].DNS.Answers[lastIdx].Type
}
tmpAnswerTypeID, err := dnsQueryTypeToID(answerTypeName)
if err == nil {
answerTypeID = tmpAnswerTypeID
} // swallow error otherwise and don't set the answer type ID
}
if answersSetBuilder.Len() == 0 {
answersSetBuilder.WriteString(header.EmptyField)
}
// from Sam: WARNING the way we handle data in RITA uses a floating time and splits
// on the . in a time string. As such this needs to be a floating point
// number. If we change the ingestion to handle floating timestamps this
// can be changed
for _, sourceIP := range util.SelectPublicPrivateIPs(outputData[i].Host.IP) {
values := []string{
fmt.Sprintf("%.6f", float64(goStartTime.UnixNano())/1e9), // "ts"
header.UnsetField, // "uid"
sourceIP, // "id.orig_h"
header.UnsetField, // "id.orig_p"
header.UnsetField, // "id.resp_h"
header.UnsetField, // "id.resp_p",
header.UnsetField, // "proto"
header.UnsetField, // "trans_id"
header.UnsetField, // "rtt"
outputData[i].DNS.Question.Name, // "query"
header.UnsetField, // "qclass"
header.UnsetField, // "qclass_name",
answerTypeID, // "qtype"
answerTypeName, // "qtype_name"
header.UnsetField, // "rcode"
header.UnsetField, // "rcode_name"
header.UnsetField, // "AA"
header.UnsetField, // "TC"
header.UnsetField, // "RD"
header.UnsetField, // "RA"
header.UnsetField, // "Z",
answersSetBuilder.String(), // "answers"
header.UnsetField, // "TTLs"
header.UnsetField, // "rejected"
outputData[i].Agent.Hostname, // "agent_hostname"
outputData[i].Agent.ID, // "agent_uuid"
}
lastIdx := len(values) - 1
for j := 0; j < lastIdx; j++ {
outputBuilder.WriteString(values[j])
outputBuilder.WriteString(separator)
}
outputBuilder.WriteString(values[lastIdx])
outputBuilder.WriteString("\n")
}
}
output = outputBuilder.String()
return output, err
}
func (c DnsTSV) HandlesECSRecord(data input.ECSRecord) bool {
return data.Event.Provider == "Microsoft-Windows-Sysmon" && data.Event.Code.String() == "22"
}
func init() {
RegisteredTSVFileTypes = append(RegisteredTSVFileTypes, DnsTSV{})
}