diff --git a/e2e/go.mod b/e2e/go.mod
index 44d14afd..328ed660 100644
--- a/e2e/go.mod
+++ b/e2e/go.mod
@@ -34,6 +34,7 @@ require (
 	dario.cat/mergo v1.0.2 // indirect
 	filippo.io/edwards25519 v1.1.0 // indirect
 	github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c // indirect
+	github.com/Azure/go-ntlmssp v0.1.1 // indirect
 	github.com/BobuSumisu/aho-corasick v1.0.3 // indirect
 	github.com/DefangLabs/secret-detector v0.0.0-20250403165618-22662109213e // indirect
 	github.com/Masterminds/goutils v1.1.1 // indirect
diff --git a/e2e/go.sum b/e2e/go.sum
index 04236c5f..fef3f46e 100644
--- a/e2e/go.sum
+++ b/e2e/go.sum
@@ -53,6 +53,8 @@ github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6 h1:He8af
 github.com/AdaLogics/go-fuzz-headers v0.0.0-20240806141605-e8a1dd7889d6/go.mod h1:8o94RPi1/7XTJvwPpRSzSUedZrtlirdB3r9Z20bi2f8=
 github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c h1:udKWzYgxTojEKWjV8V+WSxDXJ4NFATAsZjh8iIbsQIg=
 github.com/Azure/go-ansiterm v0.0.0-20250102033503-faa5f7b0171c/go.mod h1:xomTg63KZ2rFqZQzSB4Vz2SUXa1BpHTVz9L5PTmPC4E=
+github.com/Azure/go-ntlmssp v0.1.1 h1:l+FM/EEMb0U9QZE7mKNEDw5Mu3mFiaa2GKOoTSsNDPw=
+github.com/Azure/go-ntlmssp v0.1.1/go.mod h1:NYqdhxd/8aAct/s4qSYZEerdPuH1liG2/X9DiVTbhpk=
 github.com/BobuSumisu/aho-corasick v1.0.3 h1:uuf+JHwU9CHP2Vx+wAy6jcksJThhJS9ehR8a+4nPE9g=
 github.com/BobuSumisu/aho-corasick v1.0.3/go.mod h1:hm4jLcvZKI2vRF2WDU1N4p/jpWtpOzp3nLmi9AzX/XE=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
diff --git a/go.mod b/go.mod
index 2ccba870..07d8dde1 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,7 @@ module github.com/Infisical/infisical-merge
 go 1.25.9
 
 require (
+	github.com/Azure/go-ntlmssp v0.1.1
 	github.com/BobuSumisu/aho-corasick v1.0.3
 	github.com/Masterminds/sprig/v3 v3.3.0
 	github.com/awnumar/memguard v0.23.0
diff --git a/go.sum b/go.sum
index 8ca629d6..2b2740c3 100644
--- a/go.sum
+++ b/go.sum
@@ -49,6 +49,8 @@ dario.cat/mergo v1.0.1/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
 filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
+github.com/Azure/go-ntlmssp v0.1.1 h1:l+FM/EEMb0U9QZE7mKNEDw5Mu3mFiaa2GKOoTSsNDPw=
+github.com/Azure/go-ntlmssp v0.1.1/go.mod h1:NYqdhxd/8aAct/s4qSYZEerdPuH1liG2/X9DiVTbhpk=
 github.com/BobuSumisu/aho-corasick v1.0.3 h1:uuf+JHwU9CHP2Vx+wAy6jcksJThhJS9ehR8a+4nPE9g=
 github.com/BobuSumisu/aho-corasick v1.0.3/go.mod h1:hm4jLcvZKI2vRF2WDU1N4p/jpWtpOzp3nLmi9AzX/XE=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
diff --git a/packages/pam/handlers/mssql/proxy.go b/packages/pam/handlers/mssql/proxy.go
index 5073ba99..514657ee 100644
--- a/packages/pam/handlers/mssql/proxy.go
+++ b/packages/pam/handlers/mssql/proxy.go
@@ -9,6 +9,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/Azure/go-ntlmssp"
 	"github.com/Infisical/infisical-merge/packages/pam/session"
 	"github.com/rs/zerolog/log"
 )
@@ -18,6 +19,8 @@ type MssqlProxyConfig struct {
 	InjectUsername string
 	InjectPassword string
 	InjectDatabase string
+	InjectDomain   string
+	AuthMethod     string // "sql-login" or "ntlm"
 	EnableTLS      bool
 	TLSConfig      *tls.Config
 	SessionID      string
@@ -231,7 +234,19 @@ func (p *MssqlProxy) connectAndAuthenticateToServer() (net.Conn, []*TDSPacket, e
 		log.Info().Str("sessionID", p.config.SessionID).Msg("TLS established with server")
 	}
 
-	// 4. Send LOGIN7 with injected credentials
+	if p.config.AuthMethod == "ntlm" {
+		return p.authenticateNTLM(serverConn)
+	}
+	return p.authenticateSQL(serverConn)
+}
+
+func (p *MssqlProxy) authenticateSQL(serverConn net.Conn) (_ net.Conn, _ []*TDSPacket, retErr error) {
+	defer func() {
+		if retErr != nil {
+			serverConn.Close()
+		}
+	}()
+
 	loginMsg := &Login7Message{
 		Username: p.config.InjectUsername,
 		Password: p.config.InjectPassword,
@@ -247,7 +262,6 @@ func (p *MssqlProxy) connectAndAuthenticateToServer() (net.Conn, []*TDSPacket, e
 		Payload:  loginMsg.Encode(),
 	}
 	if err := loginPkt.Write(serverConn); err != nil {
-		serverConn.Close()
 		return nil, nil, fmt.Errorf("send login to server: %w", err)
 	}
 
@@ -257,11 +271,8 @@ func (p *MssqlProxy) connectAndAuthenticateToServer() (net.Conn, []*TDSPacket, e
 		Int("loginPktLen", len(loginPkt.Payload)+TDSHeaderSize).
 		Msg("Sent LOGIN7 to server")
 
-	// 5. Read login response - forward to client
-	log.Info().Str("sessionID", p.config.SessionID).Msg("Waiting for login response...")
 	response, err := ReadAllPackets(serverConn)
 	if err != nil {
-		serverConn.Close()
 		return nil, nil, fmt.Errorf("read login response: %w", err)
 	}
 	log.Info().
@@ -271,11 +282,9 @@ func (p *MssqlProxy) connectAndAuthenticateToServer() (net.Conn, []*TDSPacket, e
 
 	respPayload := CombinePayloads(response)
 	if ContainsToken(respPayload, TokenError) {
-		serverConn.Close()
 		return nil, nil, fmt.Errorf("server authentication failed")
 	}
 	if !ContainsToken(respPayload, TokenLoginAck) {
-		serverConn.Close()
 		return nil, nil, fmt.Errorf("no login ack from server")
 	}
 
@@ -283,6 +292,98 @@ func (p *MssqlProxy) connectAndAuthenticateToServer() (net.Conn, []*TDSPacket, e
 	return serverConn, response, nil
 }
 
+func (p *MssqlProxy) authenticateNTLM(serverConn net.Conn) (_ net.Conn, _ []*TDSPacket, retErr error) {
+	defer func() {
+		if retErr != nil {
+			serverConn.Close()
+		}
+	}()
+
+	negotiate, err := ntlmssp.NewNegotiateMessage(p.config.InjectDomain, "infisical-proxy")
+	if err != nil {
+		return nil, nil, fmt.Errorf("create NTLM negotiate message: %w", err)
+	}
+
+	loginMsg := &Login7Message{
+		Database: p.config.InjectDatabase,
+		AppName:  "Infisical PAM Proxy",
+		Hostname: "infisical-proxy",
+		SSPIData: negotiate,
+	}
+
+	loginPkt := &TDSPacket{
+		Type:     PacketTypeLogin7,
+		Status:   StatusEOM,
+		PacketID: 1,
+		Payload:  loginMsg.Encode(),
+	}
+	if err := loginPkt.Write(serverConn); err != nil {
+		return nil, nil, fmt.Errorf("send NTLM login to server: %w", err)
+	}
+
+	log.Info().
+		Str("sessionID", p.config.SessionID).
+		Str("domain", p.config.InjectDomain).
+		Str("user", p.config.InjectUsername).
+		Msg("Sent LOGIN7 with NTLM negotiate to server")
+
+	challengeResponse, err := ReadAllPackets(serverConn)
+	if err != nil {
+		return nil, nil, fmt.Errorf("read NTLM challenge: %w", err)
+	}
+
+	challengePayload := CombinePayloads(challengeResponse)
+
+	challengeToken, err := ExtractSSPIToken(challengePayload)
+	if err != nil {
+		if ContainsToken(challengePayload, TokenError) {
+			return nil, nil, fmt.Errorf("server rejected NTLM negotiate")
+		}
+		return nil, nil, fmt.Errorf("extract NTLM challenge: %w", err)
+	}
+
+	log.Info().
+		Str("sessionID", p.config.SessionID).
+		Int("challengeLen", len(challengeToken)).
+		Msg("Received NTLM challenge from server")
+
+	ntlmUsername := p.config.InjectDomain + "\\" + p.config.InjectUsername
+	authenticate, err := ntlmssp.ProcessChallenge(challengeToken, ntlmUsername, p.config.InjectPassword, true)
+	if err != nil {
+		return nil, nil, fmt.Errorf("process NTLM challenge: %w", err)
+	}
+
+	sspiPkt := &TDSPacket{
+		Type:     PacketTypeSSPI,
+		Status:   StatusEOM,
+		PacketID: 1,
+		Payload:  authenticate,
+	}
+	if err := sspiPkt.Write(serverConn); err != nil {
+		return nil, nil, fmt.Errorf("send NTLM authenticate: %w", err)
+	}
+
+	log.Info().
+		Str("sessionID", p.config.SessionID).
+		Msg("Sent NTLM authenticate to server")
+
+	response, err := ReadAllPackets(serverConn)
+	if err != nil {
+		return nil, nil, fmt.Errorf("read NTLM login response: %w", err)
+	}
+
+	respPayload := CombinePayloads(response)
+	if ContainsToken(respPayload, TokenError) {
+		return nil, nil, fmt.Errorf("NTLM authentication failed")
+	}
+	if !ContainsToken(respPayload, TokenLoginAck) {
+		return nil, nil, fmt.Errorf("no login ack after NTLM authentication")
+	}
+
+	log.Info().Str("sessionID", p.config.SessionID).Msg("MSSQL NTLM authentication successful")
+	return serverConn, response, nil
+}
+
 func (p *MssqlProxy) proxyToServer(client, server net.Conn, errCh chan error) {
 	defer func() {
 		if r := recover(); r != nil {
diff --git a/packages/pam/handlers/mssql/tds.go b/packages/pam/handlers/mssql/tds.go
index fe40845e..5e6b4dbe 100644
--- a/packages/pam/handlers/mssql/tds.go
+++ b/packages/pam/handlers/mssql/tds.go
@@ -53,6 +53,17 @@ const (
 	MaxPackets    = 100
 )
 
+var ntlmsspSignature = []byte("NTLMSSP\x00")
+
+// ExtractSSPIToken finds the NTLM token in a TDS server response by scanning for the NTLMSSP signature.
+func ExtractSSPIToken(payload []byte) ([]byte, error) {
+	idx := bytes.Index(payload, ntlmsspSignature)
+	if idx < 0 {
+		return nil, fmt.Errorf("no NTLMSSP token found in server response")
+	}
+	return payload[idx:], nil
+}
+
 // TDSPacket represents a TDS packet
 type TDSPacket struct {
 	Type     uint8
@@ -294,6 +305,7 @@ type Login7Message struct {
 	Password string
 	AppName  string
 	Database string
+	SSPIData []byte
 }
 
 // ParseLogin7 parses a LOGIN7 message (extracts only what we need)
@@ -324,7 +336,8 @@ const (
 	fSetLang = 0x80
 
 	// OptionFlags2
-	fODBC = 0x02
+	fODBC        = 0x02
+	fIntSecurity = 0x80 // Integrated Security (SSPI/NTLM)
 )
 
 // Encode serializes the LOGIN7 message
@@ -341,9 +354,19 @@ func (m *Login7Message) Encode() []byte {
 	m.Header.OptionFlags1 = fUseDB | fSetLang
 	m.Header.OptionFlags2 = fODBC
 
+	useSSPI := len(m.SSPIData) > 0
+
 	hostname := encodeUTF16(m.Hostname)
-	username := encodeUTF16(m.Username)
-	password := manglePassword(m.Password)
+	var username, password []byte
+	if useSSPI {
+		// NTLM: username and password are empty in LOGIN7; auth is via SSPI blob
+		username = nil
+		password = nil
+		m.Header.OptionFlags2 |= fIntSecurity
+	} else {
+		username = encodeUTF16(m.Username)
+		password = manglePassword(m.Password)
+	}
 	appname := encodeUTF16(m.AppName)
 	database := encodeUTF16(m.Database)
 	cltIntName := encodeUTF16("ODBC") // Client interface name
@@ -385,12 +408,24 @@ func (m *Login7Message) Encode() []byte {
 	offset += uint16(len(database))
 
 	m.Header.SSPIOffset = offset
-	m.Header.SSPILength = 0
+	if useSSPI {
+		sspiLen := len(m.SSPIData)
+		if sspiLen < 65535 {
+			m.Header.SSPILength = uint16(sspiLen)
+			m.Header.SSPILongLength = 0
+		} else {
+			m.Header.SSPILength = 0
+			m.Header.SSPILongLength = uint32(sspiLen)
+		}
+		offset += uint16(sspiLen)
+	} else {
+		m.Header.SSPILength = 0
+		m.Header.SSPILongLength = 0
+	}
 	m.Header.AtchDBFileOffset = offset
 	m.Header.AtchDBFileLength = 0
 	m.Header.ChangePasswordOff = offset
 	m.Header.ChangePasswordLen = 0
-	m.Header.SSPILongLength = 0
 
 	m.Header.Length = uint32(offset)
 
@@ -404,6 +439,9 @@ func (m *Login7Message) Encode() []byte {
 	buf.Write(appname)
 	buf.Write(cltIntName)
 	buf.Write(database)
+	if useSSPI {
+		buf.Write(m.SSPIData)
+	}
 
 	return buf.Bytes()
 }
diff --git a/packages/pam/pam-proxy.go b/packages/pam/pam-proxy.go
index edf273af..f57077a0 100644
--- a/packages/pam/pam-proxy.go
+++ b/packages/pam/pam-proxy.go
@@ -313,6 +313,8 @@ func HandlePAMProxy(ctx context.Context, conn *tls.Conn, pamConfig *GatewayPAMCo
 			InjectUsername: credentials.Username,
 			InjectPassword: credentials.Password,
 			InjectDatabase: credentials.Database,
+			InjectDomain:   credentials.Domain,
+			AuthMethod:     credentials.AuthMethod,
 			EnableTLS:      credentials.SSLEnabled,
 			TLSConfig:      tlsConfig,
 			SessionID:      pamConfig.SessionId,