Keylogger.
rule win_aytoke_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2022-05-16" 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 = "20220513" malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26" malpedia_version = "20220516" 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 = { 3b7d14 7d0f 8a16 8b85d8fbffff } // n = 4, score = 200 // 3b7d14 | cmp edi, dword ptr [ebp + 0x14] // 7d0f | jge 0x11 // 8a16 | mov dl, byte ptr [esi] // 8b85d8fbffff | mov eax, dword ptr [ebp - 0x428] $sequence_1 = { 1e 1f 2021 2223 244d 4d 4d } // n = 7, score = 200 // 1e | push ds // 1f | pop ds // 2021 | and byte ptr [ecx], ah // 2223 | and ah, byte ptr [ebx] // 244d | and al, 0x4d // 4d | dec ebp // 4d | dec ebp $sequence_2 = { 75e9 e9???????? 33c0 8bff 0fb78808374100 66898c05fcfdffff 83c002 } // n = 7, score = 200 // 75e9 | jne 0xffffffeb // e9???????? | // 33c0 | xor eax, eax // 8bff | mov edi, edi // 0fb78808374100 | movzx ecx, word ptr [eax + 0x413708] // 66898c05fcfdffff | mov word ptr [ebp + eax - 0x204], cx // 83c002 | add eax, 2 $sequence_3 = { c70016000000 e8???????? 895de0 395de0 } // n = 4, score = 200 // c70016000000 | mov dword ptr [eax], 0x16 // e8???????? | // 895de0 | mov dword ptr [ebp - 0x20], ebx // 395de0 | cmp dword ptr [ebp - 0x20], ebx $sequence_4 = { 50 e8???????? 59 83f8ff 741b } // n = 5, score = 200 // 50 | push eax // e8???????? | // 59 | pop ecx // 83f8ff | cmp eax, -1 // 741b | je 0x1d $sequence_5 = { 8b10 ffd2 8b8594f9ffff 50 ff15???????? } // n = 5, score = 200 // 8b10 | mov edx, dword ptr [eax] // ffd2 | call edx // 8b8594f9ffff | mov eax, dword ptr [ebp - 0x66c] // 50 | push eax // ff15???????? | $sequence_6 = { 88500a 8d85e0fdffff 68???????? 50 e8???????? 8bf0 83c408 } // n = 7, score = 200 // 88500a | mov byte ptr [eax + 0xa], dl // 8d85e0fdffff | lea eax, [ebp - 0x220] // 68???????? | // 50 | push eax // e8???????? | // 8bf0 | mov esi, eax // 83c408 | add esp, 8 $sequence_7 = { 8b4e04 8d95bcf9ffff 52 8d85f8f9ffff } // n = 4, score = 200 // 8b4e04 | mov ecx, dword ptr [esi + 4] // 8d95bcf9ffff | lea edx, [ebp - 0x644] // 52 | push edx // 8d85f8f9ffff | lea eax, [ebp - 0x608] $sequence_8 = { 7409 8b34b560884100 eb07 8b34b52c884100 } // n = 4, score = 200 // 7409 | je 0xb // 8b34b560884100 | mov esi, dword ptr [esi*4 + 0x418860] // eb07 | jmp 9 // 8b34b52c884100 | mov esi, dword ptr [esi*4 + 0x41882c] $sequence_9 = { 0f84ff000000 e8???????? ff4804 7811 e8???????? 8bd0 } // n = 6, score = 200 // 0f84ff000000 | je 0x105 // e8???????? | // ff4804 | dec dword ptr [eax + 4] // 7811 | js 0x13 // e8???????? | // 8bd0 | mov edx, eax condition: 7 of them and filesize < 425984 }
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