Actor(s): BuhTrap
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rule win_buhtrap_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-03-28" version = "1" description = "Detects win.buhtrap." 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.buhtrap" malpedia_rule_date = "20230328" malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d" malpedia_version = "20230407" 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???????? 59 59 84c0 0f8435010000 } // n = 5, score = 500 // e8???????? | // 59 | pop ecx // 59 | pop ecx // 84c0 | test al, al // 0f8435010000 | je 0x13b $sequence_1 = { 8945cc e8???????? 6a12 5a b9???????? } // n = 5, score = 400 // 8945cc | mov dword ptr [ebp - 0x34], eax // e8???????? | // 6a12 | push 0x12 // 5a | pop edx // b9???????? | $sequence_2 = { a1???????? 56 68???????? 57 8b08 } // n = 5, score = 400 // a1???????? | // 56 | push esi // 68???????? | // 57 | push edi // 8b08 | mov ecx, dword ptr [eax] $sequence_3 = { 8bfc 8bc8 a5 a5 a5 e8???????? 83c40c } // n = 7, score = 400 // 8bfc | mov edi, esp // 8bc8 | mov ecx, eax // a5 | movsd dword ptr es:[edi], dword ptr [esi] // a5 | movsd dword ptr es:[edi], dword ptr [esi] // a5 | movsd dword ptr es:[edi], dword ptr [esi] // e8???????? | // 83c40c | add esp, 0xc $sequence_4 = { 6a05 50 ff15???????? 85c0 7506 } // n = 5, score = 400 // 6a05 | push 5 // 50 | push eax // ff15???????? | // 85c0 | test eax, eax // 7506 | jne 8 $sequence_5 = { 52 0f45c8 81c900010804 51 } // n = 4, score = 400 // 52 | push edx // 0f45c8 | cmovne ecx, eax // 81c900010804 | or ecx, 0x4080100 // 51 | push ecx $sequence_6 = { e8???????? 50 ffd3 8b0d???????? } // n = 4, score = 400 // e8???????? | // 50 | push eax // ffd3 | call ebx // 8b0d???????? | $sequence_7 = { ff15???????? 85c0 75c7 eb02 b301 } // n = 5, score = 400 // ff15???????? | // 85c0 | test eax, eax // 75c7 | jne 0xffffffc9 // eb02 | jmp 4 // b301 | mov bl, 1 $sequence_8 = { 6a05 8d442424 50 ff35???????? 89742434 89742438 } // n = 6, score = 100 // 6a05 | push 5 // 8d442424 | lea eax, [esp + 0x24] // 50 | push eax // ff35???????? | // 89742434 | mov dword ptr [esp + 0x34], esi // 89742438 | mov dword ptr [esp + 0x38], esi $sequence_9 = { 8bf0 59 3bf7 750d ff75fc } // n = 5, score = 100 // 8bf0 | mov esi, eax // 59 | pop ecx // 3bf7 | cmp esi, edi // 750d | jne 0xf // ff75fc | push dword ptr [ebp - 4] $sequence_10 = { ffd7 ff742418 e8???????? 59 ff7624 8bc5 } // n = 6, score = 100 // ffd7 | call edi // ff742418 | push dword ptr [esp + 0x18] // e8???????? | // 59 | pop ecx // ff7624 | push dword ptr [esi + 0x24] // 8bc5 | mov eax, ebp $sequence_11 = { 83783403 757d 53 53 } // n = 4, score = 100 // 83783403 | cmp dword ptr [eax + 0x34], 3 // 757d | jne 0x7f // 53 | push ebx // 53 | push ebx $sequence_12 = { 894644 668b4704 59 6689463c } // n = 4, score = 100 // 894644 | mov dword ptr [esi + 0x44], eax // 668b4704 | mov ax, word ptr [edi + 4] // 59 | pop ecx // 6689463c | mov word ptr [esi + 0x3c], ax $sequence_13 = { ff15???????? 50 ffd6 85c0 750c } // n = 5, score = 100 // ff15???????? | // 50 | push eax // ffd6 | call esi // 85c0 | test eax, eax // 750c | jne 0xe $sequence_14 = { a1???????? 33c3 56 8b35???????? 8944241c 8d442418 } // n = 6, score = 100 // a1???????? | // 33c3 | xor eax, ebx // 56 | push esi // 8b35???????? | // 8944241c | mov dword ptr [esp + 0x1c], eax // 8d442418 | lea eax, [esp + 0x18] condition: 7 of them and filesize < 131072 }
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