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/*
This Yara ruleset is under the GNU-GPLv2 license (http://www.gnu.org/licenses/gpl-2.0.html) and open to any user or organization, as long as you use it under this license.
*/
rule Misdat_Backdoor_Packed
{
meta:
author = "Cylance SPEAR Team"
note = "Probably Prone to False Positive"
strings:
$upx = {33 2E 30 33 00 55 50 58 21}
$send = {00 00 00 73 65 6E 64 00 00 00}
$delphi_sec_pe = {50 45 00 00 4C 01 03 00 19 5E 42 2A}
$shellexec = {00 00 00 53 68 65 6C 6C 45 78 65 63 75 74 65 57 00 00 00}
condition:
filesize < 100KB and $upx and $send and $delphi_sec_pe and $shellexec
}
rule MiSType_Backdoor_Packed
{
meta:
author = "Cylance SPEAR Team"
note = "Probably Prone to False Positive"
strings:
$upx = {33 2E 30 33 00 55 50 58 21}
$send_httpquery = {00 00 00 48 74 74 70 51 75 65 72 79 49 6E 66 6F 41 00 00 73 65 6E 64 00 00}
$delphi_sec_pe = {50 45 00 00 4C 01 03 00 19 5E 42 2A}
condition:
filesize < 100KB and $upx and $send_httpquery and $delphi_sec_pe
}
rule Misdat_Backdoor
{
meta:
author = "Cylance SPEAR Team"
/* Decode Function
CODE:00406C71 8B 55 F4 mov edx, [ebp+var_C]
CODE:00406C74 8A 54 1A FF mov dl, [edx+ebx-1]
CODE:00406C78 8B 4D F8 mov ecx, [ebp+var_8]
CODE:00406C7B C1 E9 08 shr ecx, 8
CODE:00406C7E 32 D1 xor dl, cl
CODE:00406C80 88 54 18 FF mov [eax+ebx-1], dl
CODE:00406C84 8B 45 F4 mov eax, [ebp+var_C]
CODE:00406C87 0F B6 44 18 FF movzx eax, byte ptr [eax+ebx-1]
CODE:00406C8C 03 45 F8 add eax, [ebp+var_8]
CODE:00406C8F 69 C0 D9 DB 00 00 imul eax, 0DBD9h
CODE:00406C95 05 3B DA 00 00 add eax, 0DA3Bh
CODE:00406C9A 89 45 F8 mov [ebp+var_8], eax
CODE:00406C9D 43 inc ebx
CODE:00406C9E 4E dec esi
CODE:00406C9F 75 C9 jnz short loc_406C6A
*/
strings:
$imul = {03 45 F8 69 C0 D9 DB 00 00 05 3B DA 00 00}
$delphi = {50 45 00 00 4C 01 08 00 19 5E 42 2A}
condition:
$imul and $delphi
}
rule SType_Backdoor
{
meta:
author = "Cylance SPEAR Team"
/* Decode Function
8B 1A mov ebx, [edx]
8A 1B mov bl, [ebx]
80 EB 02 sub bl, 2
8B 74 24 08 mov esi, [esp+14h+var_C]
32 1E xor bl, [esi]
8B 31 mov esi, [ecx]
88 1E mov [esi], bl
8B 1A mov ebx, [edx]
43 inc ebx
89 1A mov [edx], ebx
8B 19 mov ebx, [ecx]
43 inc ebx
89 19 mov [ecx], ebx
48 dec eax
75 E2 jnz short loc_40EAC6
*/
strings:
$stype = "stype=info&data="
$mmid = "?mmid="
$status = "&status=run succeed"
$mutex = "_KB10B2D1_CIlFD2C"
$decode = {8B 1A 8A 1B 80 EB 02 8B 74 24 08 32 1E 8B 31 88 1E 8B 1A 43}
condition:
$stype or ($mmid and $status) or $mutex or $decode
}
rule Zlib_Backdoor
{
meta:
author = "Cylance SPEAR Team"
/* String
C7 45 FC 00 04 00 00 mov [ebp+Memory], 400h
C6 45 D8 50 mov [ebp+Str], 'P'
C6 45 D9 72 mov [ebp+var_27], 'r'
C6 45 DA 6F mov [ebp+var_26], 'o'
C6 45 DB 78 mov [ebp+var_25], 'x'
C6 45 DC 79 mov [ebp+var_24], 'y'
C6 45 DD 2D mov [ebp+var_23], '-'
C6 45 DE 41 mov [ebp+var_22], 'A'
C6 45 DF 75 mov [ebp+var_21], 'u'
C6 45 E0 74 mov [ebp+var_20], 't'
C6 45 E1 68 mov [ebp+var_1F], 'h'
C6 45 E2 65 mov [ebp+var_1E], 'e'
C6 45 E3 6E mov [ebp+var_1D], 'n'
C6 45 E4 74 mov [ebp+var_1C], 't'
C6 45 E5 69 mov [ebp+var_1B], 'i'
C6 45 E6 63 mov [ebp+var_1A], 'c'
C6 45 E7 61 mov [ebp+var_19], 'a'
C6 45 E8 74 mov [ebp+var_18], 't'
C6 45 E9 65 mov [ebp+var_17], 'e'
C6 45 EA 3A mov [ebp+var_16], ':'
C6 45 EB 20 mov [ebp+var_15], ' '
C6 45 EC 4E mov [ebp+var_14], 'N'
C6 45 ED 54 mov [ebp+var_13], 'T'
C6 45 EE 4C mov [ebp+var_12], 'L'
C6 45 EF 4D mov [ebp+var_11], 'M'
C6 45 F0 20 mov [ebp+var_10], ' '
*/
strings:
$auth = {C6 45 D8 50 C6 45 D9 72 C6 45 DA 6F C6 45 DB 78 C6 45 DC 79 C6 45 DD 2D}
$auth2 = {C7 45 FC 00 04 00 00 C6 45 ?? 50 C6 45 ?? 72 C6 45 ?? 6F}
$ntlm = "NTLM" wide
condition:
($auth or $auth2) and $ntlm
}