Gootkit is a banking trojan, where large parts are written in javascript (node.JS). It jumps to C/C++-library functions for various tasks.
rule win_gootkit_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2019-11-26" version = "1" description = "autogenerated rule brought to you by yara-signator" tool = "yara-signator 0.1a" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.gootkit" malpedia_version = "20190204" malpedia_license = "CC BY-NC-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 / approach will be published in the near future 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 = { f7f1 81c260ea0000 52 ff15???????? } // n = 4, score = 1400 // f7f1 | div ecx // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | $sequence_1 = { 8bc1 0f57c0 56 57 } // n = 4, score = 1200 // 8bc1 | mov eax, ecx // 0f57c0 | xorps xmm0, xmm0 // 56 | push esi // 57 | push edi $sequence_2 = { 56 ffd7 8bd0 33db 33c9 85d2 740e } // n = 7, score = 1200 // 56 | push esi // ffd7 | call edi // 8bd0 | mov edx, eax // 33db | xor ebx, ebx // 33c9 | xor ecx, ecx // 85d2 | test edx, edx // 740e | je 0x10 $sequence_3 = { 56 ff75f8 ff15???????? 8bd8 85db 7431 3bfb } // n = 7, score = 1200 // 56 | push esi // ff75f8 | push dword ptr [ebp - 8] // ff15???????? | // 8bd8 | mov ebx, eax // 85db | test ebx, ebx // 7431 | je 0x33 // 3bfb | cmp edi, ebx $sequence_4 = { 85d2 7458 03cb 897df8 } // n = 4, score = 1200 // 85d2 | test edx, edx // 7458 | je 0x5a // 03cb | add ecx, ebx // 897df8 | mov dword ptr [ebp - 8], edi $sequence_5 = { 6a00 53 ff15???????? eb06 } // n = 4, score = 1200 // 6a00 | push 0 // 53 | push ebx // ff15???????? | // eb06 | jmp 8 $sequence_6 = { c1cb0d 03d8 41 3bca 72f2 335df0 } // n = 6, score = 1200 // c1cb0d | ror ebx, 0xd // 03d8 | add ebx, eax // 41 | inc ecx // 3bca | cmp ecx, edx // 72f2 | jb 0xfffffff4 // 335df0 | xor ebx, dword ptr [ebp - 0x10] $sequence_7 = { 8d51ff 035710 8d41ff f7d0 23d0 8b45fc } // n = 6, score = 1200 // 8d51ff | lea edx, [ecx - 1] // 035710 | add edx, dword ptr [edi + 0x10] // 8d41ff | lea eax, [ecx - 1] // f7d0 | not eax // 23d0 | and edx, eax // 8b45fc | mov eax, dword ptr [ebp - 4] $sequence_8 = { 52 50 8b4510 99 52 50 8b450c } // n = 7, score = 1100 // 52 | push edx // 50 | push eax // 8b4510 | mov eax, dword ptr [ebp + 0x10] // 99 | cdq // 52 | push edx // 50 | push eax // 8b450c | mov eax, dword ptr [ebp + 0xc] $sequence_9 = { 50 8b4508 8b00 99 52 } // n = 5, score = 800 // 50 | push eax // 8b4508 | mov eax, dword ptr [ebp + 8] // 8b00 | mov eax, dword ptr [eax] // 99 | cdq // 52 | push edx $sequence_10 = { 7514 c705???????????????? c705???????????????? 8be5 } // n = 4, score = 700 // 7514 | jne 0x16 // c705???????????????? | // c705???????????????? | // 8be5 | mov esp, ebp $sequence_11 = { e8???????? 6a0c 6a08 ff15???????? 50 } // n = 5, score = 700 // e8???????? | // 6a0c | push 0xc // 6a08 | push 8 // ff15???????? | // 50 | push eax $sequence_12 = { e8???????? 8d45fc 50 6a01 6a01 } // n = 5, score = 500 // e8???????? | // 8d45fc | lea eax, [ebp - 4] // 50 | push eax // 6a01 | push 1 // 6a01 | push 1 $sequence_13 = { 57 ff15???????? 8bf0 8975f8 } // n = 4, score = 400 // 57 | push edi // ff15???????? | // 8bf0 | mov esi, eax // 8975f8 | mov dword ptr [ebp - 8], esi $sequence_14 = { 8d4602 5e 5b 5d } // n = 4, score = 400 // 8d4602 | lea eax, [esi + 2] // 5e | pop esi // 5b | pop ebx // 5d | pop ebp $sequence_15 = { 8bd9 57 8b7d0c 56 57 ff7508 e8???????? } // n = 7, score = 400 // 8bd9 | mov ebx, ecx // 57 | push edi // 8b7d0c | mov edi, dword ptr [ebp + 0xc] // 56 | push esi // 57 | push edi // ff7508 | push dword ptr [ebp + 8] // e8???????? | $sequence_16 = { e8???????? 85c0 740d 6810270000 } // n = 4, score = 400 // e8???????? | // 85c0 | test eax, eax // 740d | je 0xf // 6810270000 | push 0x2710 $sequence_17 = { 8bec 53 56 8b7510 8bd9 57 8b7d0c } // n = 7, score = 400 // 8bec | mov ebp, esp // 53 | push ebx // 56 | push esi // 8b7510 | mov esi, dword ptr [ebp + 0x10] // 8bd9 | mov ebx, ecx // 57 | push edi // 8b7d0c | mov edi, dword ptr [ebp + 0xc] $sequence_18 = { 55 8bec 8b4510 40 } // n = 4, score = 400 // 55 | push ebp // 8bec | mov ebp, esp // 8b4510 | mov eax, dword ptr [ebp + 0x10] // 40 | inc eax $sequence_19 = { 56 8b7510 8bd9 8b4d0c 57 0fbe7e01 8d5602 } // n = 7, score = 400 // 56 | push esi // 8b7510 | mov esi, dword ptr [ebp + 0x10] // 8bd9 | mov ebx, ecx // 8b4d0c | mov ecx, dword ptr [ebp + 0xc] // 57 | push edi // 0fbe7e01 | movsx edi, byte ptr [esi + 1] // 8d5602 | lea edx, [esi + 2] $sequence_20 = { 0fbf143e eb04 0fbe143e 8b450c 8d0c02 2bd6 034d10 } // n = 7, score = 300 // 0fbf143e | movsx edx, word ptr [esi + edi] // eb04 | jmp 6 // 0fbe143e | movsx edx, byte ptr [esi + edi] // 8b450c | mov eax, dword ptr [ebp + 0xc] // 8d0c02 | lea ecx, [edx + eax] // 2bd6 | sub edx, esi // 034d10 | add ecx, dword ptr [ebp + 0x10] $sequence_21 = { 5d c20c00 55 8bec c70101000000 } // n = 5, score = 300 // 5d | pop ebp // c20c00 | ret 0xc // 55 | push ebp // 8bec | mov ebp, esp // c70101000000 | mov dword ptr [ecx], 1 $sequence_22 = { 50 ff15???????? 8b8544ffffff 5f } // n = 4, score = 300 // 50 | push eax // ff15???????? | // 8b8544ffffff | mov eax, dword ptr [ebp - 0xbc] // 5f | pop edi $sequence_23 = { 0f104820 0f114710 0f104030 0f114f20 0f104840 0f114730 } // n = 6, score = 200 // 0f104820 | movups xmm1, xmmword ptr [eax + 0x20] // 0f114710 | movups xmmword ptr [edi + 0x10], xmm0 // 0f104030 | movups xmm0, xmmword ptr [eax + 0x30] // 0f114f20 | movups xmmword ptr [edi + 0x20], xmm1 // 0f104840 | movups xmm1, xmmword ptr [eax + 0x40] // 0f114730 | movups xmmword ptr [edi + 0x30], xmm0 $sequence_24 = { ff15???????? 8bd0 83fa01 7e18 } // n = 4, score = 200 // ff15???????? | // 8bd0 | mov edx, eax // 83fa01 | cmp edx, 1 // 7e18 | jle 0x1a $sequence_25 = { 0f104010 0f110f 0f104820 0f114710 } // n = 4, score = 200 // 0f104010 | movups xmm0, xmmword ptr [eax + 0x10] // 0f110f | movups xmmword ptr [edi], xmm1 // 0f104820 | movups xmm1, xmmword ptr [eax + 0x20] // 0f114710 | movups xmmword ptr [edi + 0x10], xmm0 $sequence_26 = { 8d4864 ff15???????? ffc3 83fb0a 7cd5 33c0 } // n = 6, score = 200 // 8d4864 | lea ecx, [eax + 0x64] // ff15???????? | // ffc3 | inc ebx // 83fb0a | cmp ebx, 0xa // 7cd5 | jl 0xffffffd7 // 33c0 | xor eax, eax $sequence_27 = { 8b4070 894770 be01000000 ff15???????? } // n = 4, score = 200 // 8b4070 | mov eax, dword ptr [eax + 0x70] // 894770 | mov dword ptr [edi + 0x70], eax // be01000000 | mov esi, 1 // ff15???????? | $sequence_28 = { 0f114f20 0f104840 0f114730 0f104050 0f114f40 0f104860 0f114750 } // n = 7, score = 200 // 0f114f20 | movups xmmword ptr [edi + 0x20], xmm1 // 0f104840 | movups xmm1, xmmword ptr [eax + 0x40] // 0f114730 | movups xmmword ptr [edi + 0x30], xmm0 // 0f104050 | movups xmm0, xmmword ptr [eax + 0x50] // 0f114f40 | movups xmmword ptr [edi + 0x40], xmm1 // 0f104860 | movups xmm1, xmmword ptr [eax + 0x60] // 0f114750 | movups xmmword ptr [edi + 0x50], xmm0 $sequence_29 = { 0f114740 0f104850 0f114f50 0f104060 0f114760 8b4070 894770 } // n = 7, score = 200 // 0f114740 | movups xmmword ptr [edi + 0x40], xmm0 // 0f104850 | movups xmm1, xmmword ptr [eax + 0x50] // 0f114f50 | movups xmmword ptr [edi + 0x50], xmm1 // 0f104060 | movups xmm0, xmmword ptr [eax + 0x60] // 0f114760 | movups xmmword ptr [edi + 0x60], xmm0 // 8b4070 | mov eax, dword ptr [eax + 0x70] // 894770 | mov dword ptr [edi + 0x70], eax $sequence_30 = { 85c0 7510 8d4864 ff15???????? } // n = 4, score = 200 // 85c0 | test eax, eax // 7510 | jne 0x12 // 8d4864 | lea ecx, [eax + 0x64] // ff15???????? | condition: 7 of them }
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