475 lines
15 KiB
Go
475 lines
15 KiB
Go
// Package redis provides a zgrab2 Module that probes for redis services.
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// The default port for redis is TCP 6379, and it is a cleartext protocol
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// defined at https://redis.io/topics/protocol.
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// Servers can be configured to require (cleartext) password authentication,
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// which is omitted from our probe by default (pass --password <your password>
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// to supply one).
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// Further, admins can rename commands, so even if authentication is not
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// required we may not get the expected output.
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// However, we should always get output in the expected format, which is fairly
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// distinct. The probe sends a sequence of commands and checks that the response
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// is well-formed redis data, which should be possible whatever the
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// configuration.
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package redis
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import (
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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log "github.com/sirupsen/logrus"
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"github.com/zmap/zgrab2"
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"gopkg.in/yaml.v2"
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)
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// Flags contains redis-specific command-line flags.
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type Flags struct {
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zgrab2.BaseFlags
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CustomCommands string `long:"custom-commands" description:"Pathname for JSON/YAML file that contains extra commands to execute. WARNING: This is sent in the clear."`
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Mappings string `long:"mappings" description:"Pathname for JSON/YAML file that contains mappings for command names."`
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MaxInputFileSize int64 `long:"max-input-file-size" default:"102400" description:"Maximum size for either input file."`
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Password string `long:"password" description:"Set a password to use to authenticate to the server. WARNING: This is sent in the clear."`
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DoInline bool `long:"inline" description:"Send commands using the inline syntax"`
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Verbose bool `long:"verbose" description:"More verbose logging, include debug fields in the scan results"`
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}
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// Module implements the zgrab2.Module interface
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type Module struct {
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}
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// Scanner implements the zgrab2.Scanner interface
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type Scanner struct {
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config *Flags
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commandMappings map[string]string
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customCommands []string
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}
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// scan holds the state for the scan of an individual target
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type scan struct {
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scanner *Scanner
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result *Result
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target *zgrab2.ScanTarget
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conn *Connection
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close func()
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}
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// Result is the struct that is returned by the scan.
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// If authentication is required, most responses can have the value
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// "(error: NOAUTH Authentication required.)"
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type Result struct {
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// Commands is the list of commands actually sent to the server, serialized
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// in inline format (e.g. COMMAND arg1 "arg 2" arg3)
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Commands []string `json:"commands,omitempty" zgrab:"debug"`
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// RawCommandOutput is the output returned by the server for each command sent;
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// the index in RawCommandOutput matches the index in Commands.
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RawCommandOutput [][]byte `json:"raw_command_output,omitempty" zgrab:"debug"`
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// PingResponse is the response from the server, should be the simple string
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// "PONG".
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// NOTE: This is invoked *before* calling AUTH, so this may return an auth
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// required error even if --password is provided.
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PingResponse string `json:"ping_response,omitempty"`
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// AuthResponse is only included if --password is set.
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AuthResponse string `json:"auth_response,omitempty"`
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// InfoResponse is the response from the INFO command: "Lines can contain a
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// section name (starting with a # character) or a property. All the
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// properties are in the form of field:value terminated by \r\n."
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InfoResponse string `json:"info_response,omitempty"`
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// Version is read from the InfoResponse (the field "server_version"), if
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// present.
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Version string `json:"version,omitempty"`
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// Major is the version's major number.
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Major *uint32 `json:"major,omitempty"`
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// Minor is the version's minor number.
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Minor *uint32 `json:"minor,omitempty"`
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// Patchlevel is the version's patchlevel number.
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Patchlevel *uint32 `json:"patchlevel,omitempty"`
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// OS is read from the InfoResponse (the field "os"), if present. It specifies
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// the OS the redis server is running.
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OS string `json:"os,omitempty"`
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// ArchBits is read from the InfoResponse (the field "arch_bits"), if present.
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// It specifies the architecture bits (32 or 64) the redis server used to build.
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ArchBits string `json:"arch_bits,omitempty"`
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// Mode is read from the InfoResponse (the field "redis_mode"), if present.
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// It specifies the mode the redis server is running, either cluster or standalone.
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Mode string `json:"mode,omitempty"`
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// GitSha1 is read from the InfoResponse (the field "redis_git_sha1"), if present.
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// It specifies the Git Sha 1 the redis server used.
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GitSha1 string `json:"git_sha1,omitempty"`
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// BuildID is read from the InfoResponse (the field "redis_build_id"), if present.
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// It specifies the Build ID of the redis server.
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BuildID string `json:"build_id,omitempty"`
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// GCCVersion is read from the InfoResponse (the field "gcc_version"), if present.
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// It specifies the version of the GCC compiler used to compile the Redis server.
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GCCVersion string `json:"gcc_version,omitempty"`
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// MemAllocator is read from the InfoResponse (the field "mem_allocator"), if present.
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// It specifies the memory allocator.
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MemAllocator string `json:"mem_allocator,omitempty"`
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// Uptime is read from the InfoResponse (the field "uptime_in_seconds"), if present.
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// It specifies the number of seconds since Redis server start.
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Uptime uint32 `json:"uptime_in_seconds,omitempty"`
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// UsedMemory is read from the InfoResponse (the field "used_memory"), if present.
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// It specifies the total number of bytes allocated by Redis using its allocator.
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UsedMemory uint32 `json:"used_memory,omitempty"`
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// ConnectionsReceived is read from the InfoResponse (the field "total_connections_received"),
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// if present. It specifies the total number of connections accepted by the server.
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ConnectionsReceived uint32 `json:"total_connections_received,omitempty"`
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// CommandsProcessed is read from the InfoResponse (the field "total_commands_processed"),
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// if present. It specifies the total number of commands processed by the server.
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CommandsProcessed uint32 `json:"total_commands_processed,omitempty"`
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// NonexistentResponse is the response to the non-existent command; even if
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// auth is required, this may give a different error than existing commands.
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NonexistentResponse string `json:"nonexistent_response,omitempty"`
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// CustomResponses is an array that holds the commands, arguments, and
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// responses from user-inputted commands.
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CustomResponses []CustomResponse `json:"custom_responses,omitempty"`
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// QuitResponse is the response from the QUIT command -- should be the
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// simple string "OK" even when authentication is required, unless the
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// QUIT command was renamed.
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QuitResponse string `json:"quit_response,omitempty"`
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}
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// RegisterModule registers the zgrab2 module
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func RegisterModule() {
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var module Module
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_, err := zgrab2.AddCommand("redis", "redis", "Probe for redis", 6379, &module)
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if err != nil {
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log.Fatal(err)
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}
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}
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// NewFlags provides an empty instance of the flags that will be filled in by the framework
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func (module *Module) NewFlags() interface{} {
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return new(Flags)
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}
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// NewScanner provides a new scanner instance
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func (module *Module) NewScanner() zgrab2.Scanner {
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return new(Scanner)
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}
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// Validate checks that the flags are valid
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func (flags *Flags) Validate(args []string) error {
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return nil
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}
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// Help returns the module's help string
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func (flags *Flags) Help() string {
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return ""
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}
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// Init initializes the scanner
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func (scanner *Scanner) Init(flags zgrab2.ScanFlags) error {
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f, _ := flags.(*Flags)
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scanner.config = f
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err := scanner.initCommands()
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if err != nil {
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log.Fatal(err)
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}
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return nil
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}
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// InitPerSender initializes the scanner for a given sender
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func (scanner *Scanner) InitPerSender(senderID int) error {
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return nil
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}
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// GetName returns the name of the scanner
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func (scanner *Scanner) GetName() string {
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return scanner.config.Name
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}
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// GetTrigger returns the Trigger defined in the Flags.
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func (scanner *Scanner) GetTrigger() string {
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return scanner.config.Trigger
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}
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// Close cleans up the scanner.
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func (scan *scan) Close() {
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defer scan.close()
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}
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func getUnmarshaler(file string) (func([]byte, interface{}) error, error) {
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var unmarshaler func([]byte, interface{}) error
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switch ext := filepath.Ext(file); ext {
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case ".json":
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unmarshaler = json.Unmarshal
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case ".yaml", ".yml":
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unmarshaler = yaml.Unmarshal
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default:
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err := fmt.Errorf("file type %s not valid", ext)
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return nil, err
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}
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return unmarshaler, nil
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}
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func (scanner *Scanner) getFileContents(file string, output interface{}) error {
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unmarshaler, err := getUnmarshaler(file)
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if err != nil {
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return err
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}
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fileStat, err := os.Stat(file)
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if err != nil {
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return err
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}
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if fileStat.Size() > scanner.config.MaxInputFileSize {
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err = fmt.Errorf("input file too large")
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return err
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}
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fileContent, err := ioutil.ReadFile(file)
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if err != nil {
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return err
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}
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err = unmarshaler([]byte(fileContent), output)
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if err != nil {
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return err
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}
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return nil
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}
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// Initializes the command mappings
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func (scanner *Scanner) initCommands() error {
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scanner.commandMappings = map[string]string{
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"PING": "PING",
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"AUTH": "AUTH",
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"INFO": "INFO",
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"NONEXISTENT": "NONEXISTENT",
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"QUIT": "QUIT",
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}
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if scanner.config.CustomCommands != "" {
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var customCommands []string
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err := scanner.getFileContents(scanner.config.CustomCommands, &customCommands)
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if err != nil {
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return err
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}
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scanner.customCommands = customCommands
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}
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// User supplied a file for updated command mappings
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if scanner.config.Mappings != "" {
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var mappings map[string]string
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err := scanner.getFileContents(scanner.config.Mappings, &mappings)
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if err != nil {
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return err
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}
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for origCommand, newCommand := range mappings {
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scanner.commandMappings[strings.ToUpper(origCommand)] = strings.ToUpper(newCommand)
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}
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}
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return nil
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}
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// SendCommand sends the given command/args to the server, using the scanner's
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// configuration, and drop the command/output into the result.
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func (scan *scan) SendCommand(cmd string, args ...string) (RedisValue, error) {
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exec := scan.conn.SendCommand
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scan.result.Commands = append(scan.result.Commands, getInlineCommand(cmd, args...))
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if scan.scanner.config.DoInline {
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exec = scan.conn.SendInlineCommand
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}
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ret, err := exec(cmd, args...)
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if err != nil {
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return nil, err
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}
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scan.result.RawCommandOutput = append(scan.result.RawCommandOutput, ret.Encode())
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return ret, nil
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}
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// StartScan opens a connection to the target and sets up a scan instance for it
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func (scanner *Scanner) StartScan(target *zgrab2.ScanTarget) (*scan, error) {
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conn, err := target.Open(&scanner.config.BaseFlags)
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if err != nil {
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return nil, err
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}
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return &scan{
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target: target,
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scanner: scanner,
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result: &Result{},
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conn: &Connection{
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scanner: scanner,
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conn: conn,
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},
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close: func() { conn.Close() },
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}, nil
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}
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// Force the response into a string. Used when you expect a human-readable
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// string.
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func forceToString(val RedisValue) string {
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switch v := val.(type) {
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case SimpleString:
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return string(v)
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case BulkString:
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return string([]byte(v))
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case Integer:
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return fmt.Sprintf("%d", v)
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case ErrorMessage:
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return fmt.Sprintf("(Error: %s)", string(v))
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case NullType:
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return "<null>"
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case RedisArray:
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return "(Unexpected array)"
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default:
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panic("unreachable")
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}
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}
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// Protocol returns the protocol identifer for the scanner.
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func (scanner *Scanner) Protocol() string {
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return "redis"
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}
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// Converts the string to a Uint32 if possible. If not, returns 0 (the zero value of a uin32)
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func convToUint32(s string) uint32 {
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s64, err := strconv.ParseUint(s, 10, 32)
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if err != nil {
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return 0
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}
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return uint32(s64)
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}
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// Scan executes the following commands:
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// 1. PING
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// 2. (only if --password is provided) AUTH <password>
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// 3. INFO
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// 4. NONEXISTENT
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// 5. (only if --custom-commands is provided) CustomCommands <args>
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// 6. QUIT
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// The responses for each of these is logged, and if INFO succeeds, the version
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// is scraped from it.
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func (scanner *Scanner) Scan(target zgrab2.ScanTarget) (zgrab2.ScanStatus, interface{}, error) {
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// ping, info, quit
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scan, err := scanner.StartScan(&target)
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if err != nil {
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return zgrab2.TryGetScanStatus(err), nil, err
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}
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defer scan.Close()
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result := scan.result
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pingResponse, err := scan.SendCommand(scanner.commandMappings["PING"])
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if err != nil {
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// If the first command fails (as opposed to succeeding but returning an
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// ErrorMessage response), then flag the probe as having failed.
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return zgrab2.TryGetScanStatus(err), nil, err
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}
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// From this point forward, we always return a non-nil result, implying that
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// we have positively identified that a redis service is present.
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result.PingResponse = forceToString(pingResponse)
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if scanner.config.Password != "" {
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authResponse, err := scan.SendCommand(scanner.commandMappings["AUTH"], scanner.config.Password)
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if err != nil {
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return zgrab2.TryGetScanStatus(err), result, err
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}
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result.AuthResponse = forceToString(authResponse)
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}
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infoResponse, err := scan.SendCommand(scanner.commandMappings["INFO"])
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if err != nil {
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return zgrab2.TryGetScanStatus(err), result, err
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}
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result.InfoResponse = forceToString(infoResponse)
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if infoResponseBulk, ok := infoResponse.(BulkString); ok {
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for _, line := range strings.Split(string(infoResponseBulk), "\r\n") {
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linePrefixSuffix := strings.SplitN(line, ":", 2)
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prefix := linePrefixSuffix[0]
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var suffix string
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if len(linePrefixSuffix) > 1 {
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suffix = linePrefixSuffix[1]
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}
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switch prefix {
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case "redis_version":
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result.Version = suffix
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versionSegments := strings.SplitN(suffix, ".", 3)
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if len(versionSegments) > 0 {
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major := convToUint32(versionSegments[0])
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result.Major = &major
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}
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if len(versionSegments) > 1 {
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minor := convToUint32(versionSegments[1])
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result.Minor = &minor
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}
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if len(versionSegments) > 2 {
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patchlevel := convToUint32(versionSegments[2])
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result.Patchlevel = &patchlevel
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}
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case "os":
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result.OS = suffix
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case "arch_bits":
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result.ArchBits = suffix
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case "redis_mode":
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result.Mode = suffix
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case "redis_git_sha1":
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result.GitSha1 = suffix
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case "redis_build_id":
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result.BuildID = suffix
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case "gcc_version":
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result.GCCVersion = suffix
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case "mem_allocator":
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result.MemAllocator = suffix
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case "uptime_in_seconds":
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result.Uptime = convToUint32(suffix)
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case "used_memory":
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result.UsedMemory = convToUint32(suffix)
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case "total_connections_received":
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result.ConnectionsReceived = convToUint32(suffix)
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case "total_commands_processed":
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result.CommandsProcessed = convToUint32(suffix)
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}
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}
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}
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bogusResponse, err := scan.SendCommand(scanner.commandMappings["NONEXISTENT"])
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if err != nil {
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return zgrab2.TryGetScanStatus(err), result, err
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}
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result.NonexistentResponse = forceToString(bogusResponse)
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for i := range scanner.customCommands {
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fullCmd := strings.Fields(scanner.customCommands[i])
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resp, err := scan.SendCommand(fullCmd[0], fullCmd[1:]...)
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if err != nil {
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return zgrab2.TryGetScanStatus(err), result, err
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}
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customResponse := CustomResponse{
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Command: fullCmd[0],
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Arguments: strings.Join(fullCmd[1:], " "),
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Response: forceToString(resp),
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}
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result.CustomResponses = append(result.CustomResponses, customResponse)
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}
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quitResponse, err := scan.SendCommand(scanner.commandMappings["QUIT"])
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if err != nil && err != io.EOF {
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return zgrab2.TryGetScanStatus(err), result, err
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} else if quitResponse == nil {
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quitResponse = NullValue
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}
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result.QuitResponse = forceToString(quitResponse)
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return zgrab2.SCAN_SUCCESS, &result, nil
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}
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