feat: add IMAP and POP3 plugins for mail server detection

IMAP (143/993): banner grab + LOGIN brute force
POP3 (110/995): banner grab + USER/PASS brute force
Both registered as safe default plugins with auth-check capability.

pkg/fscan/scanner.go

@@ -39,7 +39,9 @@ var defaultSafePlugins = []string{
 	"rabbitmq",
 	"rdp",
 	"redis",
+	"imap",
 	"jdwp",
+	"pop3",
 	"rsync",
 	"smb",
 	"smtp",
@@ -537,6 +539,7 @@ var serviceAuthPlugins = map[string]bool{
 	"cassandra":     true,
 	"elasticsearch": true,
 	"ftp":           true,
+	"imap":          true,
 	"kafka":         true,
 	"ldap":          true,
 	"memcached":     true,
@@ -545,6 +548,7 @@ var serviceAuthPlugins = map[string]bool{
 	"mysql":         true,
 	"neo4j":         true,
 	"oracle":        true,
+	"pop3":          true,
 	"postgresql":    true,
 	"rabbitmq":      true,
 	"redis":         true,

plugins/services/imap.go

@@ -0,0 +1,118 @@
+//go:build plugin_imap || !plugin_selective
+
+package services
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/shadow1ng/fscan/common"
+	"github.com/shadow1ng/fscan/plugins"
+)
+
+type IMAPPlugin struct {
+	plugins.BasePlugin
+}
+
+func NewIMAPPlugin() *IMAPPlugin {
+	return &IMAPPlugin{BasePlugin: plugins.NewBasePlugin("imap")}
+}
+
+func (p *IMAPPlugin) Scan(ctx context.Context, info *common.HostInfo, session *common.ScanSession) *ScanResult {
+	config := session.Config
+	timeout := config.Timeout
+	if timeout <= 0 {
+		timeout = 3 * time.Second
+	}
+
+	addr := fmt.Sprintf("%s:%d", info.Host, info.Port)
+	conn, err := session.DialTCP(ctx, "tcp", addr, timeout)
+	if err != nil {
+		return &ScanResult{Success: false, Service: "imap"}
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(timeout))
+
+	reader := bufio.NewReader(conn)
+	banner, err := reader.ReadString('\n')
+	if err != nil || !strings.Contains(banner, "OK") {
+		return &ScanResult{Success: false, Service: "imap"}
+	}
+	banner = strings.TrimSpace(banner)
+
+	serviceResult := &ScanResult{
+		Success: true,
+		Type:    plugins.ResultTypeService,
+		Service: "imap",
+		Banner:  banner,
+	}
+
+	if config.DisableBrute {
+		return serviceResult
+	}
+
+	credentials := GenerateCredentials("imap", config)
+	if len(credentials) == 0 {
+		return serviceResult
+	}
+
+	for _, cred := range credentials {
+		select {
+		case <-ctx.Done():
+			return serviceResult
+		default:
+		}
+
+		if result := p.tryLogin(ctx, info, cred, timeout, session); result != nil {
+			return result
+		}
+	}
+
+	return serviceResult
+}
+
+func (p *IMAPPlugin) tryLogin(ctx context.Context, info *common.HostInfo, cred plugins.Credential, timeout time.Duration, session *common.ScanSession) *ScanResult {
+	addr := fmt.Sprintf("%s:%d", info.Host, info.Port)
+	conn, err := session.DialTCP(ctx, "tcp", addr, timeout)
+	if err != nil {
+		return nil
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(timeout))
+
+	reader := bufio.NewReader(conn)
+	if _, err := reader.ReadString('\n'); err != nil {
+		return nil
+	}
+
+	loginCmd := fmt.Sprintf("a001 LOGIN %s %s\r\n", cred.Username, cred.Password)
+	if _, err := conn.Write([]byte(loginCmd)); err != nil {
+		return nil
+	}
+
+	response, err := reader.ReadString('\n')
+	if err != nil {
+		return nil
+	}
+
+	if strings.Contains(response, "a001 OK") {
+		_, _ = conn.Write([]byte("a002 LOGOUT\r\n"))
+		return &ScanResult{
+			Success:  true,
+			Type:     plugins.ResultTypeCredential,
+			Service:  "imap",
+			Username: cred.Username,
+			Password: cred.Password,
+		}
+	}
+	return nil
+}
+
+func init() {
+	RegisterPluginWithPorts("imap", func() Plugin {
+		return NewIMAPPlugin()
+	}, []int{143, 993})
+}

plugins/services/pop3.go

@@ -0,0 +1,124 @@
+//go:build plugin_pop3 || !plugin_selective
+
+package services
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/shadow1ng/fscan/common"
+	"github.com/shadow1ng/fscan/plugins"
+)
+
+type POP3Plugin struct {
+	plugins.BasePlugin
+}
+
+func NewPOP3Plugin() *POP3Plugin {
+	return &POP3Plugin{BasePlugin: plugins.NewBasePlugin("pop3")}
+}
+
+func (p *POP3Plugin) Scan(ctx context.Context, info *common.HostInfo, session *common.ScanSession) *ScanResult {
+	config := session.Config
+	timeout := config.Timeout
+	if timeout <= 0 {
+		timeout = 3 * time.Second
+	}
+
+	addr := fmt.Sprintf("%s:%d", info.Host, info.Port)
+	conn, err := session.DialTCP(ctx, "tcp", addr, timeout)
+	if err != nil {
+		return &ScanResult{Success: false, Service: "pop3"}
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(timeout))
+
+	reader := bufio.NewReader(conn)
+	banner, err := reader.ReadString('\n')
+	if err != nil || !strings.HasPrefix(banner, "+OK") {
+		return &ScanResult{Success: false, Service: "pop3"}
+	}
+	banner = strings.TrimSpace(banner)
+
+	serviceResult := &ScanResult{
+		Success: true,
+		Type:    plugins.ResultTypeService,
+		Service: "pop3",
+		Banner:  banner,
+	}
+
+	if config.DisableBrute {
+		return serviceResult
+	}
+
+	credentials := GenerateCredentials("pop3", config)
+	if len(credentials) == 0 {
+		return serviceResult
+	}
+
+	for _, cred := range credentials {
+		select {
+		case <-ctx.Done():
+			return serviceResult
+		default:
+		}
+
+		if result := p.tryLogin(ctx, info, cred, timeout, session); result != nil {
+			return result
+		}
+	}
+
+	return serviceResult
+}
+
+func (p *POP3Plugin) tryLogin(ctx context.Context, info *common.HostInfo, cred plugins.Credential, timeout time.Duration, session *common.ScanSession) *ScanResult {
+	addr := fmt.Sprintf("%s:%d", info.Host, info.Port)
+	conn, err := session.DialTCP(ctx, "tcp", addr, timeout)
+	if err != nil {
+		return nil
+	}
+	defer conn.Close()
+	_ = conn.SetDeadline(time.Now().Add(timeout))
+
+	reader := bufio.NewReader(conn)
+	if _, err := reader.ReadString('\n'); err != nil {
+		return nil
+	}
+
+	if _, err := fmt.Fprintf(conn, "USER %s\r\n", cred.Username); err != nil {
+		return nil
+	}
+	resp, err := reader.ReadString('\n')
+	if err != nil || !strings.HasPrefix(resp, "+OK") {
+		return nil
+	}
+
+	if _, err := fmt.Fprintf(conn, "PASS %s\r\n", cred.Password); err != nil {
+		return nil
+	}
+	resp, err = reader.ReadString('\n')
+	if err != nil {
+		return nil
+	}
+
+	if strings.HasPrefix(resp, "+OK") {
+		_, _ = conn.Write([]byte("QUIT\r\n"))
+		return &ScanResult{
+			Success:  true,
+			Type:     plugins.ResultTypeCredential,
+			Service:  "pop3",
+			Username: cred.Username,
+			Password: cred.Password,
+		}
+	}
+	return nil
+}
+
+func init() {
+	RegisterPluginWithPorts("pop3", func() Plugin {
+		return NewPOP3Plugin()
+	}, []int{110, 995})
+}