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 = "2019-07-05" version = "1" description = "autogenerated rule brought to you by yara-signator" tool = "yara-signator 0.2a" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.gootkit" malpedia_version = "20190620" 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 / approach 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 = { f7f1 81c260ea0000 52 ff15???????? } // n = 4, score = 1800 // f7f1 | div ecx // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | $sequence_1 = { f7f1 81c260ea0000 52 ff15???????? } // n = 4, score = 1800 // f7f1 | div ecx // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | $sequence_2 = { f7f1 81c260ea0000 52 ff15???????? } // n = 4, score = 1800 // f7f1 | div ecx // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | $sequence_3 = { f7f1 81c260ea0000 52 ff15???????? eb?? } // n = 5, score = 1700 // f7f1 | div ecx // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | // eb?? | $sequence_4 = { 81c260ea0000 52 ff15???????? eb?? } // n = 4, score = 1700 // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | // eb?? | $sequence_5 = { 81c260ea0000 52 ff15???????? eb?? } // n = 4, score = 1700 // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | // eb?? | $sequence_6 = { f7f1 81c260ea0000 52 ff15???????? eb?? } // n = 5, score = 1700 // f7f1 | div ecx // 81c260ea0000 | add edx, 0xea60 // 52 | push edx // ff15???????? | // eb?? | $sequence_7 = { ffd3 50 ff15???????? 8945ec 85c0 } // n = 5, score = 1500 // ffd3 | call ebx // 50 | push eax // ff15???????? | // 8945ec | mov dword ptr [ebp - 0x14], eax // 85c0 | test eax, eax $sequence_8 = { 8bc1 0f57c0 56 57 } // n = 4, score = 1500 // 8bc1 | mov eax, ecx // 0f57c0 | xorps xmm0, xmm0 // 56 | push esi // 57 | push edi $sequence_9 = { 85f6 74?? 46 2bde 03d8 } // n = 5, score = 1500 // 85f6 | test esi, esi // 74?? | // 46 | inc esi // 2bde | sub ebx, esi // 03d8 | add ebx, eax $sequence_10 = { 33c9 c745f804000000 41 33f6 85c0 8d45f8 50 } // n = 7, score = 1500 // 33c9 | xor ecx, ecx // c745f804000000 | mov dword ptr [ebp - 8], 4 // 41 | inc ecx // 33f6 | xor esi, esi // 85c0 | test eax, eax // 8d45f8 | lea eax, [ebp - 8] // 50 | push eax $sequence_11 = { 51 8bd7 8bce e8???????? 59 85c0 0f8????????? } // n = 7, score = 1500 // 51 | push ecx // 8bd7 | mov edx, edi // 8bce | mov ecx, esi // e8???????? | // 59 | pop ecx // 85c0 | test eax, eax // 0f8????????? | $sequence_12 = { 52 50 8b4510 99 52 50 8b450c } // n = 7, score = 1200 // 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_13 = { 75?? 8b7df4 32c0 8b4de4 } // n = 4, score = 1200 // 75?? | // 8b7df4 | mov edi, dword ptr [ebp - 0xc] // 32c0 | xor al, al // 8b4de4 | mov ecx, dword ptr [ebp - 0x1c] $sequence_14 = { 52 50 8b4510 99 52 50 8b450c } // n = 7, score = 1200 // 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_15 = { 50 8b4508 8b00 99 52 } // n = 5, score = 1000 // 50 | push eax // 8b4508 | mov eax, dword ptr [ebp + 8] // 8b00 | mov eax, dword ptr [eax] // 99 | cdq // 52 | push edx $sequence_16 = { 8b4508 8b00 99 52 } // n = 4, score = 1000 // 8b4508 | mov eax, dword ptr [ebp + 8] // 8b00 | mov eax, dword ptr [eax] // 99 | cdq // 52 | push edx $sequence_17 = { 8b4508 8b00 99 52 50 } // n = 5, score = 1000 // 8b4508 | mov eax, dword ptr [ebp + 8] // 8b00 | mov eax, dword ptr [eax] // 99 | cdq // 52 | push edx // 50 | push eax $sequence_18 = { 50 ff15???????? 50 ff15???????? 33c0 40 5d } // n = 7, score = 700 // 50 | push eax // ff15???????? | // 50 | push eax // ff15???????? | // 33c0 | xor eax, eax // 40 | inc eax // 5d | pop ebp $sequence_19 = { 50 50 ff15???????? 50 ff15???????? 33c0 } // n = 6, score = 700 // 50 | push eax // 50 | push eax // ff15???????? | // 50 | push eax // ff15???????? | // 33c0 | xor eax, eax $sequence_20 = { 50 50 ff15???????? 50 ff15???????? 33c0 40 } // n = 7, score = 700 // 50 | push eax // 50 | push eax // ff15???????? | // 50 | push eax // ff15???????? | // 33c0 | xor eax, eax // 40 | inc eax $sequence_21 = { 8b7510 8bd9 8b4d0c 57 0fbe7e01 8d5602 } // n = 6, score = 600 // 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_22 = { 8d4602 5e 5b 5d c20c00 } // n = 5, score = 600 // 8d4602 | lea eax, [esi + 2] // 5e | pop esi // 5b | pop ebx // 5d | pop ebp // c20c00 | ret 0xc $sequence_23 = { 8bec 53 56 8b7510 8bd9 8b4d0c 57 } // n = 7, score = 600 // 8bec | mov ebp, esp // 53 | push ebx // 56 | push esi // 8b7510 | mov esi, dword ptr [ebp + 0x10] // 8bd9 | mov ebx, ecx // 8b4d0c | mov ecx, dword ptr [ebp + 0xc] // 57 | push edi $sequence_24 = { 53 56 8b7510 8bd9 57 8b7d0c 56 } // n = 7, score = 600 // 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] // 56 | push esi $sequence_25 = { 56 8b7510 8bd9 57 8b7d0c 56 } // n = 6, score = 600 // 56 | push esi // 8b7510 | mov esi, dword ptr [ebp + 0x10] // 8bd9 | mov ebx, ecx // 57 | push edi // 8b7d0c | mov edi, dword ptr [ebp + 0xc] // 56 | push esi $sequence_26 = { ff15???????? b9bb010000 663bc1 75?? } // n = 4, score = 400 // ff15???????? | // b9bb010000 | mov ecx, 0x1bb // 663bc1 | cmp ax, cx // 75?? | $sequence_27 = { 85c0 75?? 8d4864 ff15???????? ffc3 83fb0a 7c?? } // n = 7, score = 300 // 85c0 | test eax, eax // 75?? | // 8d4864 | lea ecx, [eax + 0x64] // ff15???????? | // ffc3 | inc ebx // 83fb0a | cmp ebx, 0xa // 7c?? | $sequence_28 = { 0f114f20 0f104840 0f114730 0f104050 } // n = 4, score = 300 // 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] $sequence_29 = { 0f114740 0f104850 0f114f50 0f104060 0f114760 8b4070 894770 } // n = 7, score = 300 // 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 = { 0f110f 0f104820 0f114710 0f104030 0f114f20 0f104840 0f114730 } // n = 7, score = 300 // 0f110f | movups xmmword ptr [edi], xmm1 // 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_31 = { 0f110f 0f104820 0f114710 0f104030 } // n = 4, score = 300 // 0f110f | movups xmmword ptr [edi], xmm1 // 0f104820 | movups xmm1, xmmword ptr [eax + 0x20] // 0f114710 | movups xmmword ptr [edi + 0x10], xmm0 // 0f104030 | movups xmm0, xmmword ptr [eax + 0x30] $sequence_32 = { 0f104060 0f114760 8b4070 894770 be01000000 ff15???????? } // n = 6, score = 300 // 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 // be01000000 | mov esi, 1 // ff15???????? | $sequence_33 = { 0f110f 0f104820 0f114710 0f104030 0f114f20 } // n = 5, score = 300 // 0f110f | movups xmmword ptr [edi], xmm1 // 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 $sequence_34 = { 8d4dd0 e8???????? 5f 5e 8be5 } // n = 5, score = 200 // 8d4dd0 | lea ecx, [ebp - 0x30] // e8???????? | // 5f | pop edi // 5e | pop esi // 8be5 | mov esp, ebp $sequence_35 = { fec3 74?? 837d1800 75?? 6a20 e8???????? } // n = 6, score = 100 // fec3 | inc bl // 74?? | // 837d1800 | cmp dword ptr [ebp + 0x18], 0 // 75?? | // 6a20 | push 0x20 // e8???????? | $sequence_36 = { 50 e8???????? 83c40c 89742444 8d442444 50 ff15???????? } // n = 7, score = 100 // 50 | push eax // e8???????? | // 83c40c | add esp, 0xc // 89742444 | mov dword ptr [esp + 0x44], esi // 8d442444 | lea eax, [esp + 0x44] // 50 | push eax // ff15???????? | $sequence_37 = { c20400 55 e8???????? cc } // n = 4, score = 100 // c20400 | ret 4 // 55 | push ebp // e8???????? | // cc | int3 $sequence_38 = { 8d442434 8bcb 50 e8???????? 8d442448 } // n = 5, score = 100 // 8d442434 | lea eax, [esp + 0x34] // 8bcb | mov ecx, ebx // 50 | push eax // e8???????? | // 8d442448 | lea eax, [esp + 0x48] $sequence_39 = { 50 8d0c1f 51 53 } // n = 4, score = 100 // 50 | push eax // 8d0c1f | lea ecx, [edi + ebx] // 51 | push ecx // 53 | push ebx $sequence_40 = { 55 57 68d4d70210 56 8944244c e8???????? 55 } // n = 7, score = 100 // 55 | push ebp // 57 | push edi // 68d4d70210 | push 0x1002d7d4 // 56 | push esi // 8944244c | mov dword ptr [esp + 0x4c], eax // e8???????? | // 55 | push ebp $sequence_41 = { 8b402c 135c2414 2bf2 1b7c2414 2910 8b442410 8b401c } // n = 7, score = 100 // 8b402c | mov eax, dword ptr [eax + 0x2c] // 135c2414 | adc ebx, dword ptr [esp + 0x14] // 2bf2 | sub esi, edx // 1b7c2414 | sbb edi, dword ptr [esp + 0x14] // 2910 | sub dword ptr [eax], edx // 8b442410 | mov eax, dword ptr [esp + 0x10] // 8b401c | mov eax, dword ptr [eax + 0x1c] condition: 7 of them }
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