rule win_kimsuky_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" version = "1" description = "Detects win.kimsuky." 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.kimsuky" malpedia_rule_date = "20260916" malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6" malpedia_version = "20260917" 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 = { e8???????? 83c430 8d95f0fcffff b9???????? e8???????? } // n = 5, score = 400 // e8???????? | // 83c430 | add esp, 0x30 // 8d95f0fcffff | lea edx, [ebp - 0x310] // b9???????? | // e8???????? | $sequence_1 = { ffd6 8bd8 85db 7510 } // n = 4, score = 400 // ffd6 | call esi // 8bd8 | mov ebx, eax // 85db | test ebx, ebx // 7510 | jne 0x12 $sequence_2 = { 53 e8???????? 83c404 8bf0 6a00 } // n = 5, score = 400 // 53 | push ebx // e8???????? | // 83c404 | add esp, 4 // 8bf0 | mov esi, eax // 6a00 | push 0 $sequence_3 = { 8d85f8feffff 6a00 50 ff15???????? 8d85ecfbffff 50 } // n = 6, score = 400 // 8d85f8feffff | lea eax, [ebp - 0x108] // 6a00 | push 0 // 50 | push eax // ff15???????? | // 8d85ecfbffff | lea eax, [ebp - 0x414] // 50 | push eax $sequence_4 = { ff15???????? 85c0 7516 ff15???????? 8bd8 e8???????? } // n = 6, score = 400 // ff15???????? | // 85c0 | test eax, eax // 7516 | jne 0x18 // ff15???????? | // 8bd8 | mov ebx, eax // e8???????? | $sequence_5 = { 8bca 83e103 f3a4 8d8de4fbffff 49 } // n = 5, score = 400 // 8bca | mov ecx, edx // 83e103 | and ecx, 3 // f3a4 | rep movsb byte ptr es:[edi], byte ptr [esi] // 8d8de4fbffff | lea ecx, [ebp - 0x41c] // 49 | dec ecx $sequence_6 = { 8945fc 833d????????00 7413 b801000000 8b4dfc } // n = 5, score = 400 // 8945fc | mov dword ptr [ebp - 4], eax // 833d????????00 | // 7413 | je 0x15 // b801000000 | mov eax, 1 // 8b4dfc | mov ecx, dword ptr [ebp - 4] $sequence_7 = { 7423 6a00 8d85f0feffff 50 68???????? ff15???????? } // n = 6, score = 400 // 7423 | je 0x25 // 6a00 | push 0 // 8d85f0feffff | lea eax, [ebp - 0x110] // 50 | push eax // 68???????? | // ff15???????? | $sequence_8 = { 8d8de8fdffff e8???????? 8b4dfc 33cd e8???????? } // n = 5, score = 400 // 8d8de8fdffff | lea ecx, [ebp - 0x218] // e8???????? | // 8b4dfc | mov ecx, dword ptr [ebp - 4] // 33cd | xor ecx, ebp // e8???????? | $sequence_9 = { 4d03fa 664403df 4983c004 4983c102 664585db 75af 4c897c2468 } // n = 7, score = 300 // 4d03fa | inc ecx // 664403df | mov ecx, dword ptr [edx] // 4983c004 | dec ecx // 4983c102 | add ecx, ecx // 664585db | inc ebp // 75af | xor eax, eax // 4c897c2468 | dec eax $sequence_10 = { 4883c514 85c0 0f857affffff 4c8b7c2460 4c8b6c2420 4c8b642428 } // n = 6, score = 300 // 4883c514 | mov dword ptr [esp + 0x30], edi // 85c0 | dec eax // 0f857affffff | mov dword ptr [esp + 0x60], ebp // 4c8b7c2460 | dec eax // 4c8b6c2420 | mov ecx, dword ptr [eax + 0x18] // 4c8b642428 | inc ecx $sequence_11 = { 48897c2430 48896c2460 488b4818 41bb01000000 4c8b7120 } // n = 5, score = 300 // 48897c2430 | dec eax // 48896c2460 | mov dword ptr [esp + 0x30], edi // 488b4818 | dec eax // 41bb01000000 | mov dword ptr [esp + 0x60], ebp // 4c8b7120 | dec eax $sequence_12 = { 0f8569ffffff 418b5f28 4533c0 33d2 4883c9ff 4903de ff542468 } // n = 7, score = 300 // 0f8569ffffff | test esi, esi // 418b5f28 | jne 0xfffffe46 // 4533c0 | dec eax // 33d2 | mov ebp, dword ptr [esp + 0x60] // 4883c9ff | dec esp // 4903de | arpl word ptr [ebp + 0x3c], di // ff542468 | nop word ptr [eax + eax] $sequence_13 = { 4c8b642428 488b7c2430 488b742438 488b6c2470 4d8bc6 4d2b4730 4183bfb400000000 } // n = 7, score = 300 // 4c8b642428 | je 0x1f2 // 488b7c2430 | jne 0xffffff6f // 488b742438 | inc ecx // 488b6c2470 | mov ebx, dword ptr [edi + 0x28] // 4d8bc6 | inc ebp // 4d2b4730 | xor eax, eax // 4183bfb400000000 | xor edx, edx $sequence_14 = { 4d03d9 666666660f1f840000000000 418b0a 4903c9 4533c0 } // n = 5, score = 300 // 4d03d9 | dec eax // 666666660f1f840000000000 | mov eax, dword ptr [0x60] // 418b0a | dec eax // 4903c9 | mov dword ptr [esp + 0x30], edi // 4533c0 | dec eax $sequence_15 = { 4d85f6 0f8540feffff 488b6c2460 4c637d3c } // n = 4, score = 300 // 4d85f6 | mov dword ptr [esp + 0x60], ebp // 0f8540feffff | dec eax // 488b6c2460 | mov ecx, dword ptr [eax + 0x18] // 4c637d3c | inc ecx $sequence_16 = { 8b442468 6683f809 7508 83f809 } // n = 4, score = 200 // 8b442468 | dec esp // 6683f809 | mov ebp, dword ptr [esp + 0x20] // 7508 | dec esp // 83f809 | mov esp, dword ptr [esp + 0x28] $sequence_17 = { 8bd7 3bd8 0f94c2 85d2 7419 } // n = 5, score = 200 // 8bd7 | add ecx, 2 // 3bd8 | inc bp // 0f94c2 | test ebx, ebx // 85d2 | jne 0xffffffbd // 7419 | dec esp $sequence_18 = { 894d90 8bc1 81fb00000001 0f97c0 } // n = 4, score = 200 // 894d90 | je 0x1fd // 8bc1 | jne 0xffffff6f // 81fb00000001 | inc ecx // 0f97c0 | mov ebx, dword ptr [edi + 0x28] $sequence_19 = { 85c0 0f94c1 85c9 0f8494020000 89bda0000000 897d30 } // n = 6, score = 200 // 85c0 | dec eax // 0f94c1 | mov ebp, dword ptr [esp + 0x60] // 85c9 | dec esp // 0f8494020000 | arpl word ptr [ebp + 0x3c], di // 89bda0000000 | nop word ptr [eax + eax] // 897d30 | inc ecx $sequence_20 = { 83f809 8d7340 7405 be20000000 c68424a000000000 33d2 } // n = 6, score = 200 // 83f809 | dec eax // 8d7340 | mov dword ptr [esp + 0x60], ebp // 7405 | dec eax // be20000000 | mov ecx, dword ptr [eax + 0x18] // c68424a000000000 | inc ecx // 33d2 | mov ebx, 1 $sequence_21 = { 488d8a38000000 e9???????? 488d8a28010000 e9???????? } // n = 4, score = 200 // 488d8a38000000 | mov ebx, eax // e9???????? | // 488d8a28010000 | imul ebx, eax // e9???????? | $sequence_22 = { 8b7590 660f1f440000 837df000 0f841b020000 } // n = 4, score = 200 // 8b7590 | inc esi // 660f1f440000 | mov ebx, dword ptr [edi + ecx + 0x24] // 837df000 | dec ebp // 0f841b020000 | add edx, ecx $sequence_23 = { 898521010000 66898525010000 888527010000 8b742450 } // n = 4, score = 200 // 898521010000 | dec ecx // 66898525010000 | add ecx, 2 // 888527010000 | inc bp // 8b742450 | test ebx, ebx $sequence_24 = { 4c89642430 c744242880000000 c744242002000000 4533c9 4533c0 } // n = 5, score = 200 // 4c89642430 | mov dword ptr [ebp + 0xa0], edi // c744242880000000 | mov dword ptr [ebp + 0x30], edi // c744242002000000 | test eax, eax // 4533c9 | sete cl // 4533c0 | test ecx, ecx $sequence_25 = { 48c1e105 4c03c1 488d542470 488d4dc0 } // n = 4, score = 100 // 48c1e105 | lea esi, [ebx + 0x40] // 4c03c1 | je 7 // 488d542470 | mov eax, dword ptr [esp + 0x68] // 488d4dc0 | cmp ax, 9 $sequence_26 = { 48bfffffffffffffff7f 483bf7 0f87ea000000 488bce 4c89742468 } // n = 5, score = 100 // 48bfffffffffffffff7f | test ecx, ecx // 483bf7 | je 0x29f // 0f87ea000000 | mov ecx, edi // 488bce | test eax, eax // 4c89742468 | sete cl $sequence_27 = { 48c1e105 4c03c1 488d542438 488d8dc0000000 } // n = 4, score = 100 // 48c1e105 | mov dword ptr [ebp + 0xa0], edi // 4c03c1 | mov dword ptr [ebp + 0x30], edi // 488d542438 | mov eax, dword ptr [esp + 0x68] // 488d8dc0000000 | cmp ax, 9 $sequence_28 = { 48c1e302 4c8bc3 8d040e 488d8d94080000 898590080000 e8???????? 488d0df984fcff } // n = 7, score = 100 // 48c1e302 | jne 0x1a // 4c8bc3 | mov ebx, eax // 8d040e | imul ebx, eax // 488d8d94080000 | jne 0x18 // 898590080000 | mov ebx, eax // e8???????? | // 488d0df984fcff | imul ebx, eax $sequence_29 = { 48c1e302 4c8bc3 8d040e 488d8d24030000 898520030000 e8???????? 488d0d3354fbff } // n = 7, score = 100 // 48c1e302 | je 0x238 // 4c8bc3 | mov esi, dword ptr [ebp - 0x70] // 8d040e | nop word ptr [eax + eax] // 488d8d24030000 | mov ebx, eax // 898520030000 | imul ebx, eax // e8???????? | // 488d0d3354fbff | test eax, eax $sequence_30 = { 48b9ffffffffffffff7f 488bc1 492bc6 4883f814 0f82520d0000 4c8d7d48 } // n = 6, score = 100 // 48b9ffffffffffffff7f | je 7 // 488bc1 | mov esi, 0x20 // 492bc6 | mov dword ptr [ebp - 0x70], ecx // 4883f814 | mov eax, ecx // 0f82520d0000 | cmp ebx, 0x1000000 // 4c8d7d48 | seta al condition: 7 of them and filesize < 1021952 }