SPE/MiniFlame contains the same “main” encryption alg from ver 4.00-5.00

It looks like this:
.text:10007DDE Decrypt_str_10007DDE proc near ; CODE XREF: sub_10001223+5p .text:10007DDE ; sub_10001223+16p ... .text:10007DDE .text:10007DDE arg_0 = dword ptr 4 .text:10007DDE .text:10007DDE mov ecx, [esp+arg_0] .text:10007DE2 push esi .text:10007DE3 cmp byte ptr [ecx+0Ch], 42h .text:10007DE7 lea esi, [ecx+0Dh] .text:10007DEA jnz short loc_10007DF0 .text:10007DEC mov eax, esi .text:10007DEE pop esi .text:10007DEF retn .text:10007DF0 ; --------------------------------------------------------------------------- .text:10007DF0 .text:10007DF0 loc_10007DF0: ; CODE XREF: Decrypt_str_10007DDE+Cj .text:10007DF0 push ebx .text:10007DF1 xor ebx, ebx .text:10007DF3 xor edx, edx .text:10007DF5 cmp [ecx+0Ah], bx .text:10007DF9 jbe short loc_10007E16 .text:10007DFB .text:10007DFB loc_10007DFB: ; CODE XREF: Decrypt_str_10007DDE+36j .text:10007DFB mov al, dl .text:10007DFD add al, 6Eh .text:10007DFF imul bl .text:10007E01 mov bl, 0C2h .text:10007E03 sub bl, al .text:10007E05 sub bl, dl .text:10007E07 add [edx+esi], bl .text:10007E0A mov bl, [edx+esi] .text:10007E0D movzx eax, word ptr [ecx+0Ah] .text:10007E11 inc edx .text:10007E12 cmp edx, eax .text:10007E14 jb short loc_10007DFB .text:10007E16 .text:10007E16 loc_10007E16: ; CODE XREF: Decrypt_str_10007DDE+1Bj .text:10007E16 mov eax, esi .text:10007E18 pop ebx .text:10007E19 mov byte ptr [ecx+0Ch], 42h .text:10007E1D pop esi .text:10007E1E retn .text:10007E1E Decrypt_str_10007DDE endp .text:10007E1E .text:10007E1F .text:10007E1F ; =============== S U B R O U T I N E ======================================= .text:10007E1F .text:10007E1F .text:10007E1F srand_10007E1F proc near ; CODE XREF: sub_10003377+Dp .text:10007E1F push 0 ; Time .text:10007E21 call ds:time .text:10007E27 push eax ; Seed .text:10007E28 call ds:srand .text:10007E2E pop ecx .text:10007E2F pop ecx .text:10007E30 retn .text:10007E30 srand_10007E1F endp .text:10007E30

basically the structure is of a stream-cipher, where the generated key is not XORd, but ADDed to the encrypted byte to be decrypted. This is very similar to flame. dl is a counter, so the main thing is bl and the imul function. It’s not that complicated or novel, but still interesting.

It’s a bit strange, as the encrypted string table basically consists of some 3-tuple elements, and only the middle on is encrypted by the code above. It is similar, but not that similar to other Duqu or Flame encryption technique.

Here is some perl code to make a simple decryptor:


tobedecrypted:$t
$al=$dl;

$al= ($al+ 0x6e)%256;

$ax=$al*$bl % 65536; #imul bl?

$al=$ax % 256;

$bl= 0xc2;

$bl= ($bl -$al) %256;

$bl= ($bl -$dl) %256;

$t2= ($t+$bl) %256;

$bl= $t2;

$dl= ($dl+1) %256; #in fact dx, but dh is not used only as loop variable
$bufall2.=pack("C",$t2);

$i+=1;

if ($new==1)

{

$bl=0;

$dl=0;

}

`output buffer: $bufall2`

So after all, we can decrypt main strings. This encryption technique was not changed between 4.00-5.00 versions and also relates to USB (U) versions, too.

For v5.00 we get the following strings

bdagent.exe %yJ^ outpost.exe `icsvnt32a.ocx Global\AdvTW32Ready500WfEvent 8Global\AdvTW32SyncEvent lnkfile\shellex\IconHandler {00021401-0000-0000-C000-000000000046} dgfw (icsvnt32.ocx %windir%\system32\ %allusersprofile%\ msfrmt32.dll gGlobal\ShellTRPInitEvent Global\AdvTW32AutoDetect 8Global\MICEvent (Global\TUSEvent L1--- Global\ShlZoneSynchMutex vbtLw %allusersprofile%\mstlis.log 4|k Iphlpapi.dll Ws2_32.dll \SS_data.bmp.ppm %temp%\tksp1.tmp W%temp%\tksp2.tmp %temp%\tksp3.tmp W%temp%\tksp4.tmp %temp%\tksp7.tmp %temp%\tksp8.tmp ]ContLo.txt Cont.txt


ChannelD.txt
ChannelC.txt

ChannelB.txt

[ChannelA.txt

zFIONA

nSONIA

) Ti

hELVIS

0EVE

JC,B

DRAKE

xCHARLES

ALEX

BARBARA

tTIFFANY

pEOC

(

P%allusersprofile%\datFE2B.da1

%temp%\daa59.tmp

Q%windir%\system32\msfrmt32.dll

FiV=.

DllStartServer

P)mVu

jDllSto

77?'

lk_data.txt

%^no

inet_addr inet_ntoa htonl ntohs htons GetAdaptersInfo OGetBestInterface RearWindow detected no activity since delta started, maybe no one logged in?. +*#PFl+ RearWindow failed. RearWindow throw an exception. function returned: BARBAR BARBAR Alex ends. Result is: Alex Starts Sam ends. Result is: nH,1 Sam Starts 9Yg3d Charles ends. Result is: Charles Starts Drake ends. Result is: Drake Starts tWO8 Elvis ends. Result is: Elvis Starts Eve ends. Result is: Eve Starts Sonia ends. Result is: =1g3 Sonia Starts 'W~~ Fiona ends. Result is: )OOQ Fiona Starts S{+w\ h&K= {%mk $&FILE_NAME= &ACTION= &COMP_ID= @&LOGGED_ON= &SEC_COUNT= &SUC_CMD_ATTEMPTS= &CMD_ATTEMPTS=&COMPUTER_NAME= P&MAC= (&IP= &SERVICE_PACK= &VERSION_INFO= +&LI= &COM_B= SP v5.00H @&TOOL_B= Rdw^,Q h0T^ &PASSWORD= @&n8 UNIQUE_NUMBER= jIQ: 85.25.0.24 LifeS Q194.192.14.125 Grendercodec.info videosy nvidiastream.info nvidiadrivers.i 202.75.58.179 nvidiasoft.info syncstream.info xflashupdates.info /cgi-bin/counter.cgi KSYSTEM\CurrentControlSet\Control\TimeZoneInformation +!XQ StandardTimeBias StandardDateBias SYSTEM\CurrentControlSet\Hardware Profiles\Current\Software\Fonts PixelShader advapi32.dll Global\TRStepEvent aah/x sGlobal\MSTKCSrvEvent vqL7 %allusersprofile%\icsvntu32.ocx oC7g Global\ShlZoneDataMutex SYSTEM svchost.exe TRegNotifyChangeKeyVa "'F/ explorer KSOFTWARE\Classes\CLSID{35CEC8A3-2BE6-11D2-8773-92E220524153}\InProcServer32 SOFTWARE\Classes\CLSID{450D8FBA-AD25-11D0-98A8-0800361B1103}\InProcServer32 mydocs.dll SOFTWARE\Classes\CLSID{35CEC8A3-2BE6-11D2-8773-92E220524153}\InprocServer32 SOFTWARE\Classes\CLSID{4E14FBA2-2E22-11D1-9964-00C04FBBB345}\InprocServer32 %windir%\System32\es.dll MACHINE\SOFTWARE\Classes\CLSID{4E14FBA2-2E22-11D1-9964-00C04FBBB345}\InprocServer32 DllUnregisterServer DllRegisterServer DllGetClassObject %a+8@9 DllCanUnloadNow LSOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon PDefaultUserName 6Dq6 hNUL= kernel32.dll t_b|& uGetIfTable +iphlpapi.dll shlwapi.dll 0PathS ?A5! RevertToSelf ImpersonateLoggedOnUser XU- RegOverridePredefKey RegOpenCurrentUser OpenProcessToken LoadLibraryA cVirtualAlloc VirtualFree VirtualProtect )GetProcAddress %allusersprofile%\Wnm.tmp ProxyOverride ProxyServer ProxyEnable 0Software\Microsoft\Windows\CurrentVersion\Internet Settings www.google.com 0Deskto @Onenotem.exe &?G? Onenote.exe paltalk.exe mmc.exe d&|us mstsc.exe ypager.exe visio.exe TE$o powerpnt.exe winproj.exe k (c> notepad.exe netscape.exe putty.exe ftp.exe telnet.exe %exceed.exe H`vS sinetinfo.exe icqlite.exe icq.exe @frontpage.exe aim95.exe (aim.exe acrord32.exe |acrobat.exe Cygwin.exe msdev.exe xmsnmsgr.exe msgplus.exe hmsmsgs.exe excel.exe HWINWORD.exe msimn.exe OUTLOOK.exe Mozilla.exe firefox.exe iexplore.exe

We did not cross-check it, but strange that it’s BARBAR here and not BARBARA (might be the fault of the decryptor).
The more interesting is that everybody was so interested in the language of recent targeted malware (Duqu, Flame, Gauss) and we could not get much “language mistakes” in those cases. Compared to that this is strange:

Alex ends. Result is: Alex Starts

“Result is” is strange. “Starts” with capital S (for all functions, and all knows versions of the malware) is also strange.

p>
“RearWindow throw an exception.” – throw or throws? surely strange. This type of error was never convicted in Duqu and Flame or we were not able to find such yet.