Keylogger.
rule win_aytoke_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.aytoke." 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.aytoke" 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 = { 8b450c 8b4d10 56 57 8b7d08 8d95dcfbffff } // n = 6, score = 200 // 8b450c | mov eax, dword ptr [ebp + 0xc] // 8b4d10 | mov ecx, dword ptr [ebp + 0x10] // 56 | push esi // 57 | push edi // 8b7d08 | mov edi, dword ptr [ebp + 8] // 8d95dcfbffff | lea edx, [ebp - 0x424] $sequence_1 = { a1???????? 8b0d???????? 8b15???????? 8985a8f9ffff } // n = 4, score = 200 // a1???????? | // 8b0d???????? | // 8b15???????? | // 8985a8f9ffff | mov dword ptr [ebp - 0x658], eax $sequence_2 = { ffd2 8b8594f9ffff 50 ff15???????? } // n = 4, score = 200 // ffd2 | call edx // 8b8594f9ffff | mov eax, dword ptr [ebp - 0x66c] // 50 | push eax // ff15???????? | $sequence_3 = { 4d 4d 0b0c0d0e0f1011 1213 1415 } // n = 5, score = 200 // 4d | dec ebp // 4d | dec ebp // 0b0c0d0e0f1011 | or ecx, dword ptr [ecx + 0x11100f0e] // 1213 | adc dl, byte ptr [ebx] // 1415 | adc al, 0x15 $sequence_4 = { 7407 c6854feeffff01 6a14 ff15???????? 6890000000 ffd3 } // n = 6, score = 200 // 7407 | je 9 // c6854feeffff01 | mov byte ptr [ebp - 0x11b1], 1 // 6a14 | push 0x14 // ff15???????? | // 6890000000 | push 0x90 // ffd3 | call ebx $sequence_5 = { 83c414 8d45c8 48 8a4801 40 } // n = 5, score = 200 // 83c414 | add esp, 0x14 // 8d45c8 | lea eax, [ebp - 0x38] // 48 | dec eax // 8a4801 | mov cl, byte ptr [eax + 1] // 40 | inc eax $sequence_6 = { 881438 46 47 ebd7 8b8dd8fbffff } // n = 5, score = 200 // 881438 | mov byte ptr [eax + edi], dl // 46 | inc esi // 47 | inc edi // ebd7 | jmp 0xffffffd9 // 8b8dd8fbffff | mov ecx, dword ptr [ebp - 0x428] $sequence_7 = { 8d55ec 52 b902000000 56 8945f0 66894dec ff15???????? } // n = 7, score = 200 // 8d55ec | lea edx, [ebp - 0x14] // 52 | push edx // b902000000 | mov ecx, 2 // 56 | push esi // 8945f0 | mov dword ptr [ebp - 0x10], eax // 66894dec | mov word ptr [ebp - 0x14], cx // ff15???????? | $sequence_8 = { 4d 4d 0b0c0d0e0f1011 1213 1415 16 17 } // n = 7, score = 200 // 4d | dec ebp // 4d | dec ebp // 0b0c0d0e0f1011 | or ecx, dword ptr [ecx + 0x11100f0e] // 1213 | adc dl, byte ptr [ebx] // 1415 | adc al, 0x15 // 16 | push ss // 17 | pop ss $sequence_9 = { 8bc6 c1f805 8b048500c44100 83e61f c1e606 8d443004 } // n = 6, score = 200 // 8bc6 | mov eax, esi // c1f805 | sar eax, 5 // 8b048500c44100 | mov eax, dword ptr [eax*4 + 0x41c400] // 83e61f | and esi, 0x1f // c1e606 | shl esi, 6 // 8d443004 | lea eax, [eax + esi + 4] condition: 7 of them and filesize < 425984 }
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