Ransomware written in Nim.
rule win_unidentified_088_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" version = "1" description = "Detects win.unidentified_088." 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.unidentified_088" 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 = { 8b00 eb24 b908000000 85c0 7405 8b08 } // n = 6, score = 100 // 8b00 | mov eax, dword ptr [eax] // eb24 | jmp 0x26 // b908000000 | mov ecx, 8 // 85c0 | test eax, eax // 7405 | je 7 // 8b08 | mov ecx, dword ptr [eax] $sequence_1 = { 335de4 83c44c c1c60f 69f69335871b } // n = 4, score = 100 // 335de4 | xor ebx, dword ptr [ebp - 0x1c] // 83c44c | add esp, 0x4c // c1c60f | rol esi, 0xf // 69f69335871b | imul esi, esi, 0x1b873593 $sequence_2 = { 891424 e8???????? 8b07 807c07072f 75ce 807b2100 8b7b0c } // n = 7, score = 100 // 891424 | mov dword ptr [esp], edx // e8???????? | // 8b07 | mov eax, dword ptr [edi] // 807c07072f | cmp byte ptr [edi + eax + 7], 0x2f // 75ce | jne 0xffffffd0 // 807b2100 | cmp byte ptr [ebx + 0x21], 0 // 8b7b0c | mov edi, dword ptr [ebx + 0xc] $sequence_3 = { 48 eb03 83c8ff 89442404 891c24 e8???????? 8b06 } // n = 7, score = 100 // 48 | dec eax // eb03 | jmp 5 // 83c8ff | or eax, 0xffffffff // 89442404 | mov dword ptr [esp + 4], eax // 891c24 | mov dword ptr [esp], ebx // e8???????? | // 8b06 | mov eax, dword ptr [esi] $sequence_4 = { 83ec10 a1???????? 3901 750a b9???????? e8???????? 8b4508 } // n = 7, score = 100 // 83ec10 | sub esp, 0x10 // a1???????? | // 3901 | cmp dword ptr [ecx], eax // 750a | jne 0xc // b9???????? | // e8???????? | // 8b4508 | mov eax, dword ptr [ebp + 8] $sequence_5 = { 893424 894c2408 894350 8b4358 895354 8b535c 897c2404 } // n = 7, score = 100 // 893424 | mov dword ptr [esp], esi // 894c2408 | mov dword ptr [esp + 8], ecx // 894350 | mov dword ptr [ebx + 0x50], eax // 8b4358 | mov eax, dword ptr [ebx + 0x58] // 895354 | mov dword ptr [ebx + 0x54], edx // 8b535c | mov edx, dword ptr [ebx + 0x5c] // 897c2404 | mov dword ptr [esp + 4], edi $sequence_6 = { c705????????c0ac4200 c705????????8cea4100 c705????????08134200 c605????????01 c705????????04000000 c705????????e08c4200 c705????????93ea4100 } // n = 7, score = 100 // c705????????c0ac4200 | // c705????????8cea4100 | // c705????????08134200 | // c605????????01 | // c705????????04000000 | // c705????????e08c4200 | // c705????????93ea4100 | $sequence_7 = { e8???????? 83c410 5b 5e 5d c3 89ca } // n = 7, score = 100 // e8???????? | // 83c410 | add esp, 0x10 // 5b | pop ebx // 5e | pop esi // 5d | pop ebp // c3 | ret // 89ca | mov edx, ecx $sequence_8 = { 8b45c8 8d440604 894dcc e8???????? 8b45d4 8b4dcc 89da } // n = 7, score = 100 // 8b45c8 | mov eax, dword ptr [ebp - 0x38] // 8d440604 | lea eax, [esi + eax + 4] // 894dcc | mov dword ptr [ebp - 0x34], ecx // e8???????? | // 8b45d4 | mov eax, dword ptr [ebp - 0x2c] // 8b4dcc | mov ecx, dword ptr [ebp - 0x34] // 89da | mov edx, ebx $sequence_9 = { c705????????00000000 c705????????c0a44200 c705????????37e84100 c705????????e00c4200 c605????????01 c705????????04000000 c705????????208d4200 } // n = 7, score = 100 // c705????????00000000 | // c705????????c0a44200 | // c705????????37e84100 | // c705????????e00c4200 | // c605????????01 | // c705????????04000000 | // c705????????208d4200 | condition: 7 of them and filesize < 919552 }
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