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rule win_microcin_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.microcin." info = "autogenerated rule brought to you by yara-signator" tool = "yara-signator v0.6.0" signator_config = "callsandjumps;datarefs;binvalue" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.microcin" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" /* DISCLAIMER * The strings used in this rule have been automatically selected from the * disassembly of memory dumps and unpacked files, using YARA-Signator. * The code and documentation is published here: * https://github.com/fxb-cocacoding/yara-signator * As Malpedia is used as data source, please note that for a given * number of families, only single samples are documented. * This likely impacts the degree of generalization these rules will offer. * Take the described generation method also into consideration when you * apply the rules in your use cases and assign them confidence levels. */ strings: $sequence_0 = { c7461401000000 4d8d8680000000 418900 4989b688000000 41c7868400000004000000 4533c9 } // n = 6, score = 400 // c7461401000000 | push esi // 4d8d8680000000 | test eax, eax // 418900 | cmovne esi, edi // 4989b688000000 | push eax // 41c7868400000004000000 | call ebx // 4533c9 | test eax, eax $sequence_1 = { ff15???????? 488bcb 664489642438 488bf0 ff15???????? 0fb7cf } // n = 6, score = 400 // ff15???????? | // 488bcb | jle 0x1f // 664489642438 | push 0x104 // 488bf0 | push eax // ff15???????? | // 0fb7cf | lea eax, [ebp - 0x108] $sequence_2 = { 897e04 5b 5f 5e 5d c20400 55 } // n = 7, score = 400 // 897e04 | int3 // 5b | dec esp // 5f | lea eax, [0x1126c] // 5e | dec ecx // 5d | mov edx, esp // c20400 | dec eax // 55 | mov ecx, ebp $sequence_3 = { 8d45ac 50 6801000080 ff15???????? } // n = 4, score = 400 // 8d45ac | sub esp, 0x20 // 50 | mov ebx, ecx // 6801000080 | mov ecx, ebx // ff15???????? | $sequence_4 = { 85c0 7e18 80bc35a8feffff3a 741f 8d85a8feffff } // n = 5, score = 400 // 85c0 | jmp dword ptr [eax*4 + 0x4017d8] // 7e18 | mov dword ptr [ebp - 0x14c], 0 // 80bc35a8feffff3a | push eax // 741f | push esi // 8d85a8feffff | test eax, eax $sequence_5 = { ff15???????? 4863c8 c6840d8002000068 488d8d80020000 } // n = 4, score = 400 // ff15???????? | // 4863c8 | test eax, eax // c6840d8002000068 | jle 0x1f // 488d8d80020000 | cmp byte ptr [ebp + esi - 0x158], 0x3a $sequence_6 = { 488b0d???????? ff15???????? 4885c0 742b 488b4018 } // n = 5, score = 400 // 488b0d???????? | // ff15???????? | // 4885c0 | jle 0x1c // 742b | lea eax, [ebp - 0x54] // 488b4018 | push eax $sequence_7 = { 4885c0 742b 488b4018 488b08 8b09 ff15???????? 488bf8 } // n = 7, score = 400 // 4885c0 | push esi // 742b | call esi // 488b4018 | push 4 // 488b08 | call ebx // 8b09 | test eax, eax // ff15???????? | // 488bf8 | jle 0x1a $sequence_8 = { 50 6805100000 68ffff0000 56 8b35???????? ffd6 } // n = 6, score = 400 // 50 | inc ecx // 6805100000 | lea edx, [eax + 1] // 68ffff0000 | inc eax // 56 | push ebx // 8b35???????? | // ffd6 | dec eax $sequence_9 = { 8d85f8feffff 6804010000 50 ff15???????? 8d85f8feffff } // n = 5, score = 400 // 8d85f8feffff | push 0x128 // 6804010000 | lea eax, [ebp - 0x134] // 50 | push 0 // ff15???????? | // 8d85f8feffff | push eax $sequence_10 = { ff15???????? 4863c8 807c0c5f5c 7413 488d4c2460 ff15???????? 4863c8 } // n = 7, score = 400 // ff15???????? | // 4863c8 | cmp byte ptr [ebp + esi - 0x158], 0x3a // 807c0c5f5c | push 0xffff // 7413 | push esi // 488d4c2460 | call esi // ff15???????? | // 4863c8 | push 4 $sequence_11 = { ff15???????? 8b3d???????? 8d85e0feffff 50 } // n = 4, score = 400 // ff15???????? | // 8b3d???????? | // 8d85e0feffff | lea eax, [ebp - 0x158] // 50 | test eax, eax $sequence_12 = { 33f6 50 ffd3 85c0 7e18 } // n = 5, score = 400 // 33f6 | push eax // 50 | push esi // ffd3 | test eax, eax // 85c0 | cmovne esi, edi // 7e18 | push eax $sequence_13 = { 488b05???????? 4833c4 488985f0040000 4c8b3d???????? 4533c0 8bfa } // n = 6, score = 400 // 488b05???????? | // 4833c4 | lea eax, [ebp - 0x158] // 488985f0040000 | xor esi, esi // 4c8b3d???????? | // 4533c0 | push eax // 8bfa | call ebx $sequence_14 = { 8b1d???????? 8d85a8feffff 50 ffd3 } // n = 4, score = 400 // 8b1d???????? | // 8d85a8feffff | call esi // 50 | lea eax, [ebp - 0x54] // ffd3 | push eax $sequence_15 = { 488b1d???????? 488903 48894308 488b0d???????? } // n = 4, score = 400 // 488b1d???????? | // 488903 | push 0x10 // 48894308 | push eax // 488b0d???????? | $sequence_16 = { 7647 498bcd e8???????? 4c8d05b7120100 41b903000000 488d4c45bc 488bc1 } // n = 7, score = 200 // 7647 | mov edx, esp // 498bcd | xor ecx, ecx // e8???????? | // 4c8d05b7120100 | test eax, eax // 41b903000000 | mov ebx, ecx // 488d4c45bc | dec eax // 488bc1 | lea ecx, [0x10c95] $sequence_17 = { 6828010000 8d85ccfeffff 6a00 50 } // n = 4, score = 200 // 6828010000 | push 0x128 // 8d85ccfeffff | lea eax, [ebp - 0x134] // 6a00 | push 0 // 50 | push eax $sequence_18 = { 488d0d950c0100 ff15???????? 4885c0 7419 } // n = 4, score = 200 // 488d0d950c0100 | dec eax // ff15???????? | // 4885c0 | mov ecx, ebp // 7419 | inc ecx $sequence_19 = { 7419 488d15730c0100 488bc8 ff15???????? } // n = 4, score = 200 // 7419 | je 0x1b // 488d15730c0100 | dec eax // 488bc8 | lea edx, [0x10c73] // ff15???????? | $sequence_20 = { 7541 8b4df0 83c108 51 } // n = 4, score = 200 // 7541 | xor ecx, ecx // 8b4df0 | dec eax // 83c108 | mov dword ptr [esp + 0x20], esi // 51 | int3 $sequence_21 = { 7370 696465726167656e 742e 657865 } // n = 4, score = 200 // 7370 | jae 0x72 // 696465726167656e | imul esp, dword ptr [ebp + 0x72], 0x6e656761 // 742e | je 0x30 // 657865 | js 0x68 $sequence_22 = { 83ec08 894df8 c745fc00a40000 6a40 6800100000 } // n = 5, score = 200 // 83ec08 | mov eax, ecx // 894df8 | dec ecx // c745fc00a40000 | sub eax, ebp // 6a40 | dec eax // 6800100000 | sar eax, 1 $sequence_23 = { 53 53 56 43 } // n = 4, score = 200 // 53 | push ebx // 53 | push ebx // 56 | push esi // 43 | inc ebx $sequence_24 = { 498bd5 ff15???????? 418d7c24e7 85c0 752a 4c8d0502130100 8bd7 } // n = 7, score = 200 // 498bd5 | dec eax // ff15???????? | // 418d7c24e7 | mov ecx, eax // 85c0 | dec ecx // 752a | mov edx, ebp // 4c8d0502130100 | inc ecx // 8bd7 | lea edi, [esp - 0x19] $sequence_25 = { 8b8c8d78feffff 890c90 ebc8 e9???????? 33c0 } // n = 5, score = 200 // 8b8c8d78feffff | test eax, eax // 890c90 | dec eax // ebc8 | mov dword ptr [esp + 0x20], esi // e9???????? | // 33c0 | int3 $sequence_26 = { c745f46d737664 c745ec5f6c6569 0fbe4dee 83c101 884dee c745f872742e64 } // n = 6, score = 200 // c745f46d737664 | dec eax // c745ec5f6c6569 | sub edi, eax // 0fbe4dee | mov ebx, ecx // 83c101 | dec eax // 884dee | lea ecx, [0x10c95] // c745f872742e64 | dec eax $sequence_27 = { 8d8da0f4ffff e8???????? 8b8574dfffff 5e 8be5 } // n = 5, score = 200 // 8d8da0f4ffff | mov ecx, 3 // e8???????? | // 8b8574dfffff | dec eax // 5e | lea ecx, [ebp + eax*2 - 0x44] // 8be5 | dec eax $sequence_28 = { 8b4dfc 83c108 51 ff15???????? 8b4dfc } // n = 5, score = 200 // 8b4dfc | dec esp // 83c108 | lea eax, [0x1126c] // 51 | dec ecx // ff15???????? | // 8b4dfc | mov edx, esp $sequence_29 = { 4883ec20 8bd9 488d0d950c0100 ff15???????? } // n = 4, score = 200 // 4883ec20 | test eax, eax // 8bd9 | jne 0x2e // 488d0d950c0100 | dec esp // ff15???????? | $sequence_30 = { 8b4508 0fb608 81e107000080 7905 49 83c9f8 41 } // n = 7, score = 200 // 8b4508 | jne 0x1e // 0fb608 | dec eax // 81e107000080 | lea edx, [0x111f8] // 7905 | inc ecx // 49 | mov eax, 0x12010 // 83c9f8 | dec eax // 41 | mov ecx, ebp $sequence_31 = { e8???????? 85c0 751a 488d15f8110100 } // n = 4, score = 200 // e8???????? | // 85c0 | je 0x1e // 751a | jbe 0x49 // 488d15f8110100 | dec ecx $sequence_32 = { e8???????? cc 4c8d056c120100 498bd4 488bcd } // n = 5, score = 200 // e8???????? | // cc | mov ecx, ebp // 4c8d056c120100 | dec esp // 498bd4 | lea eax, [0x112b7] // 488bcd | inc ecx $sequence_33 = { 83c208 52 ff15???????? 6a06 ff15???????? ebcd 8be5 } // n = 7, score = 200 // 83c208 | dec esp // 52 | lea eax, [0x1126c] // ff15???????? | // 6a06 | dec eax // ff15???????? | // ebcd | mov ecx, ebp // 8be5 | test eax, eax $sequence_34 = { 726f 6e 6d 656e 7400 } // n = 5, score = 200 // 726f | jb 0x71 // 6e | outsb dx, byte ptr [esi] // 6d | insd dword ptr es:[edi], dx // 656e | outsb dx, byte ptr gs:[esi] // 7400 | je 2 $sequence_35 = { fa fa fa fa fa } // n = 5, score = 200 // fa | cli // fa | cli // fa | cli // fa | cli // fa | cli $sequence_36 = { 4c8d0574130100 488bcd 418bd4 e8???????? 33c9 85c0 } // n = 6, score = 200 // 4c8d0574130100 | lea eax, [0x11302] // 488bcd | mov edx, edi // 418bd4 | dec eax // e8???????? | // 33c9 | sub esp, 0x20 // 85c0 | mov ebx, ecx $sequence_37 = { 636373 7673 6873742e65 7865 } // n = 4, score = 200 // 636373 | arpl word ptr [ebx + 0x73], sp // 7673 | jbe 0x75 // 6873742e65 | push 0x652e7473 // 7865 | js 0x67 $sequence_38 = { 660fd645ec 660fd645f4 3d89000000 0f87b2010000 0fb68030184000 ff2485d8174000 68???????? } // n = 7, score = 100 // 660fd645ec | xor eax, eax // 660fd645f4 | add edx, 8 // 3d89000000 | push edx // 0f87b2010000 | push 6 // 0fb68030184000 | jmp 0xffffffd1 // ff2485d8174000 | mov esp, ebp // 68???????? | $sequence_39 = { 63f6 48 89d9 6a08 41 58 4f } // n = 7, score = 100 // 63f6 | arpl si, si // 48 | dec eax // 89d9 | mov ecx, ebx // 6a08 | push 8 // 41 | inc ecx // 58 | pop eax // 4f | dec edi $sequence_40 = { 50 56 c785a4fcffff24020000 ff15???????? 85c0 7431 } // n = 6, score = 100 // 50 | add esp, 8 // 56 | mov eax, dword ptr [ebp - 0x10] // c785a4fcffff24020000 | and eax, 2 // ff15???????? | // 85c0 | mov dword ptr [ebp - 0x10], eax // 7431 | jne 0x1c $sequence_41 = { 8d85f0feffff 6a00 50 e8???????? 83c408 8d95f0feffff } // n = 6, score = 100 // 8d85f0feffff | add ecx, 8 // 6a00 | push ecx // 50 | mov ecx, dword ptr [ebp - 4] // e8???????? | // 83c408 | add ecx, 8 // 8d95f0feffff | push ecx $sequence_42 = { 680000cf00 68???????? 8d842480000000 50 6a00 ff15???????? } // n = 6, score = 100 // 680000cf00 | mov dword ptr [ebp - 8], 0x642e7472 // 68???????? | // 8d842480000000 | mov ecx, dword ptr [ebp + ecx*4 - 0x188] // 50 | mov dword ptr [eax + edx*4], ecx // 6a00 | jmp 0xffffffca // ff15???????? | $sequence_43 = { 68???????? e8???????? 8b7508 c7465cf8814000 } // n = 4, score = 100 // 68???????? | // e8???????? | // 8b7508 | mov ecx, dword ptr [ebp - 4] // c7465cf8814000 | push edx $sequence_44 = { c785b4feffff00000000 ff15???????? 50 56 ff15???????? 85c0 7e0f } // n = 7, score = 100 // c785b4feffff00000000 | mov eax, dword ptr [ebp + 8] // ff15???????? | // 50 | movzx ecx, byte ptr [eax] // 56 | and ecx, 0x80000007 // ff15???????? | // 85c0 | jns 0xd // 7e0f | dec ecx $sequence_45 = { e8???????? 3d1f047008 754e 49 8b4d08 49 8b5510 } // n = 7, score = 100 // e8???????? | // 3d1f047008 | cmp eax, 0x870041f // 754e | jne 0x50 // 49 | dec ecx // 8b4d08 | mov ecx, dword ptr [ebp + 8] // 49 | dec ecx // 8b5510 | mov edx, dword ptr [ebp + 0x10] $sequence_46 = { 7523 56 8d44245c 50 } // n = 4, score = 100 // 7523 | or ecx, 0xfffffff8 // 56 | inc ecx // 8d44245c | jne 0x43 // 50 | mov ecx, dword ptr [ebp - 0x10] $sequence_47 = { 40 ebf8 55 8bec 8b450c } // n = 5, score = 100 // 40 | inc eax // ebf8 | jmp 0xfffffffa // 55 | push ebp // 8bec | mov ebp, esp // 8b450c | mov eax, dword ptr [ebp + 0xc] $sequence_48 = { 8b4060 6a40 6800100000 680c200000 6a00 8945f8 } // n = 6, score = 100 // 8b4060 | mov eax, dword ptr [eax + 0x60] // 6a40 | push 0x40 // 6800100000 | push 0x1000 // 680c200000 | push 0x200c // 6a00 | push 0 // 8945f8 | mov dword ptr [ebp - 8], eax $sequence_49 = { 7521 4c 89e1 33d2 41 b800800000 41 } // n = 7, score = 100 // 7521 | jne 0x23 // 4c | dec esp // 89e1 | mov ecx, esp // 33d2 | xor edx, edx // 41 | inc ecx // b800800000 | mov eax, 0x8000 // 41 | inc ecx condition: 7 of them and filesize < 417792 }
import "pe" rule win_microcin_w0 { meta: description = "Malware sample mentioned in Microcin technical report by Kaspersky" author = "Florian Roth" reference = "https://securelist.com/files/2017/09/Microcin_Technical-PDF_eng_final.pdf" date = "2017-09-26" hash = "49816eefcd341d7a9c1715e1f89143862d4775ba4f9730397a1e8529f5f5e200" hash = "a73f8f76a30ad5ab03dd503cc63de3a150e6ab75440c1060d75addceb4270f46" hash = "9dd9bb13c2698159eb78a0ecb4e8692fd96ca4ecb50eef194fa7479cb65efb7c" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.microcin" malpedia_version = "20170413" malpedia_license = "CC BY-NC-SA 4.0" malpedia_sharing = "TLP:WHITE" strings: $s1 = "e Class Descriptor at (" fullword ascii $s2 = ".?AVCAntiAntiAppleFrameRealClass@@" fullword ascii $s3 = ".?AVCAntiAntiAppleFrameBaseClass@@" fullword ascii $s4 = ".?AVCAppleBinRealClass@@" fullword ascii $s5 = ".?AVCAppleBinBaseClass@@" fullword ascii condition: uint16(0) == 0x5a4d and filesize < 300KB and (4 of them or pe.imphash() == "897077ca318eaf629cfe74569f10e023") }
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