rule win_brambul_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" version = "1" description = "Detects win.brambul." 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.brambul" malpedia_rule_date = "20260916" malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6" malpedia_version = "20260917" 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 = { 7e45 8b5c241c 8b6c2418 ff15???????? 2b442410 3d60ea0000 7734 } // n = 7, score = 100 // 7e45 | jle 0x47 // 8b5c241c | mov ebx, dword ptr [esp + 0x1c] // 8b6c2418 | mov ebp, dword ptr [esp + 0x18] // ff15???????? | // 2b442410 | sub eax, dword ptr [esp + 0x10] // 3d60ea0000 | cmp eax, 0xea60 // 7734 | ja 0x36 $sequence_1 = { 8dbc37604bbbf6 8bf7 c1ee10 c1e710 0bf7 } // n = 5, score = 100 // 8dbc37604bbbf6 | lea edi, [edi + esi - 0x944b4a0] // 8bf7 | mov esi, edi // c1ee10 | shr esi, 0x10 // c1e710 | shl edi, 0x10 // 0bf7 | or esi, edi $sequence_2 = { 8807 8b4d88 47 46 4a } // n = 5, score = 100 // 8807 | mov byte ptr [edi], al // 8b4d88 | mov ecx, dword ptr [ebp - 0x78] // 47 | inc edi // 46 | inc esi // 4a | dec edx $sequence_3 = { 8bd7 33d1 035054 8d9c13f87ca21f 8bd3 c1ea10 } // n = 6, score = 100 // 8bd7 | mov edx, edi // 33d1 | xor edx, ecx // 035054 | add edx, dword ptr [eax + 0x54] // 8d9c13f87ca21f | lea ebx, [ebx + edx + 0x1fa27cf8] // 8bd3 | mov edx, ebx // c1ea10 | shr edx, 0x10 $sequence_4 = { 8d542414 50 51 52 8d842494030000 68???????? 50 } // n = 7, score = 100 // 8d542414 | lea edx, [esp + 0x14] // 50 | push eax // 51 | push ecx // 52 | push edx // 8d842494030000 | lea eax, [esp + 0x394] // 68???????? | // 50 | push eax $sequence_5 = { 8bb4247c010000 b980000000 8d5624 c6460873 8bfa f3ab } // n = 6, score = 100 // 8bb4247c010000 | mov esi, dword ptr [esp + 0x17c] // b980000000 | mov ecx, 0x80 // 8d5624 | lea edx, [esi + 0x24] // c6460873 | mov byte ptr [esi + 8], 0x73 // 8bfa | mov edi, edx // f3ab | rep stosd dword ptr es:[edi], eax $sequence_6 = { 33c9 8a4e01 8bf9 8d5703 } // n = 4, score = 100 // 33c9 | xor ecx, ecx // 8a4e01 | mov cl, byte ptr [esi + 1] // 8bf9 | mov edi, ecx // 8d5703 | lea edx, [edi + 3] $sequence_7 = { 8d542464 c744246400020000 52 f3a5 e8???????? } // n = 5, score = 100 // 8d542464 | lea edx, [esp + 0x64] // c744246400020000 | mov dword ptr [esp + 0x64], 0x200 // 52 | push edx // f3a5 | rep movsd dword ptr es:[edi], dword ptr [esi] // e8???????? | $sequence_8 = { 8d942474010000 57 52 8bf0 ff15???????? } // n = 5, score = 100 // 8d942474010000 | lea edx, [esp + 0x174] // 57 | push edi // 52 | push edx // 8bf0 | mov esi, eax // ff15???????? | $sequence_9 = { 762e 83cfff 2b7de4 03c7 8b7dd8 3bce 731f } // n = 7, score = 100 // 762e | jbe 0x30 // 83cfff | or edi, 0xffffffff // 2b7de4 | sub edi, dword ptr [ebp - 0x1c] // 03c7 | add eax, edi // 8b7dd8 | mov edi, dword ptr [ebp - 0x28] // 3bce | cmp ecx, esi // 731f | jae 0x21 $sequence_10 = { 7509 8b8c85b049ffff eb02 33c9 8d8485b449ffff } // n = 5, score = 100 // 7509 | jne 0xb // 8b8c85b049ffff | mov ecx, dword ptr [ebp + eax*4 - 0xb650] // eb02 | jmp 4 // 33c9 | xor ecx, ecx // 8d8485b449ffff | lea eax, [ebp + eax*4 - 0xb64c] $sequence_11 = { 0f85ac000000 3bf9 7531 8d9d887fffff 3bc3 7427 } // n = 6, score = 100 // 0f85ac000000 | jne 0xb2 // 3bf9 | cmp edi, ecx // 7531 | jne 0x33 // 8d9d887fffff | lea ebx, [ebp - 0x8078] // 3bc3 | cmp eax, ebx // 7427 | je 0x29 $sequence_12 = { 66898dc0f5ffff 8d8dc4fdffff 8955dc 8945e0 51 8d9598e3ffff 68???????? } // n = 7, score = 100 // 66898dc0f5ffff | mov word ptr [ebp - 0xa40], cx // 8d8dc4fdffff | lea ecx, [ebp - 0x23c] // 8955dc | mov dword ptr [ebp - 0x24], edx // 8945e0 | mov dword ptr [ebp - 0x20], eax // 51 | push ecx // 8d9598e3ffff | lea edx, [ebp - 0x1c68] // 68???????? | $sequence_13 = { 3b85b849ffff 7316 8b4588 8d3438 8d85887fffff } // n = 5, score = 100 // 3b85b849ffff | cmp eax, dword ptr [ebp - 0xb648] // 7316 | jae 0x18 // 8b4588 | mov eax, dword ptr [ebp - 0x78] // 8d3438 | lea esi, [eax + edi] // 8d85887fffff | lea eax, [ebp - 0x8078] $sequence_14 = { 56 57 8b35???????? 85f6 741b } // n = 5, score = 100 // 56 | push esi // 57 | push edi // 8b35???????? | // 85f6 | test esi, esi // 741b | je 0x1d $sequence_15 = { 8b442424 8b4c2428 8d9d28030000 6804010000 53 } // n = 5, score = 100 // 8b442424 | mov eax, dword ptr [esp + 0x24] // 8b4c2428 | mov ecx, dword ptr [esp + 0x28] // 8d9d28030000 | lea ebx, [ebp + 0x328] // 6804010000 | push 0x104 // 53 | push ebx condition: 7 of them and filesize < 188416 }