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package ntlmssp
import (
"bytes"
"crypto/rand"
"encoding/binary"
"errors"
"time"
)
type authenicateMessage struct {
LmChallengeResponse []byte
NtChallengeResponse []byte
TargetName string
UserName string
// only set if negotiateFlag_NTLMSSP_NEGOTIATE_KEY_EXCH
EncryptedRandomSessionKey []byte
NegotiateFlags negotiateFlags
MIC []byte
}
type authenticateMessageFields struct {
messageHeader
LmChallengeResponse varField
NtChallengeResponse varField
TargetName varField
UserName varField
Workstation varField
_ [8]byte
NegotiateFlags negotiateFlags
}
func (m authenicateMessage) MarshalBinary() ([]byte, error) {
if !m.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATEUNICODE) {
return nil, errors.New("Only unicode is supported")
}
target, user := toUnicode(m.TargetName), toUnicode(m.UserName)
workstation := toUnicode("go-ntlmssp")
ptr := binary.Size(&authenticateMessageFields{})
f := authenticateMessageFields{
messageHeader: newMessageHeader(3),
NegotiateFlags: m.NegotiateFlags,
LmChallengeResponse: newVarField(&ptr, len(m.LmChallengeResponse)),
NtChallengeResponse: newVarField(&ptr, len(m.NtChallengeResponse)),
TargetName: newVarField(&ptr, len(target)),
UserName: newVarField(&ptr, len(user)),
Workstation: newVarField(&ptr, len(workstation)),
}
f.NegotiateFlags.Unset(negotiateFlagNTLMSSPNEGOTIATEVERSION)
b := bytes.Buffer{}
if err := binary.Write(&b, binary.LittleEndian, &f); err != nil {
return nil, err
}
if err := binary.Write(&b, binary.LittleEndian, &m.LmChallengeResponse); err != nil {
return nil, err
}
if err := binary.Write(&b, binary.LittleEndian, &m.NtChallengeResponse); err != nil {
return nil, err
}
if err := binary.Write(&b, binary.LittleEndian, &target); err != nil {
return nil, err
}
if err := binary.Write(&b, binary.LittleEndian, &user); err != nil {
return nil, err
}
if err := binary.Write(&b, binary.LittleEndian, &workstation); err != nil {
return nil, err
}
return b.Bytes(), nil
}
//ProcessChallenge crafts an AUTHENTICATE message in response to the CHALLENGE message
//that was received from the server
func ProcessChallenge(challengeMessageData []byte, user, password string) ([]byte, error) {
if user == "" && password == "" {
return nil, errors.New("Anonymous authentication not supported")
}
var cm challengeMessage
if err := cm.UnmarshalBinary(challengeMessageData); err != nil {
return nil, err
}
if cm.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATELMKEY) {
return nil, errors.New("Only NTLM v2 is supported, but server requested v1 (NTLMSSP_NEGOTIATE_LM_KEY)")
}
if cm.NegotiateFlags.Has(negotiateFlagNTLMSSPNEGOTIATEKEYEXCH) {
return nil, errors.New("Key exchange requested but not supported (NTLMSSP_NEGOTIATE_KEY_EXCH)")
}
am := authenicateMessage{
UserName: user,
TargetName: cm.TargetName,
NegotiateFlags: cm.NegotiateFlags,
}
timestamp := cm.TargetInfo[avIDMsvAvTimestamp]
if timestamp == nil { // no time sent, take current time
ft := uint64(time.Now().UnixNano()) / 100
ft += 116444736000000000 // add time between unix & windows offset
timestamp = make([]byte, 8)
binary.LittleEndian.PutUint64(timestamp, ft)
}
clientChallenge := make([]byte, 8)
rand.Reader.Read(clientChallenge)
ntlmV2Hash := getNtlmV2Hash(password, user, cm.TargetName)
am.NtChallengeResponse = computeNtlmV2Response(ntlmV2Hash,
cm.ServerChallenge[:], clientChallenge, timestamp, cm.TargetInfoRaw)
if cm.TargetInfoRaw == nil {
am.LmChallengeResponse = computeLmV2Response(ntlmV2Hash,
cm.ServerChallenge[:], clientChallenge)
}
return am.MarshalBinary()
}
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