Ransomware.
rule win_gibberish_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-07-11" version = "1" description = "Detects win.gibberish." 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.gibberish" malpedia_rule_date = "20230705" malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41" malpedia_version = "20230715" 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 = { 83c10c e9???????? 8b4de0 83c11c e9???????? 8b4de0 83c144 } // n = 7, score = 100 // 83c10c | add ecx, 0xc // e9???????? | // 8b4de0 | mov ecx, dword ptr [ebp - 0x20] // 83c11c | add ecx, 0x1c // e9???????? | // 8b4de0 | mov ecx, dword ptr [ebp - 0x20] // 83c144 | add ecx, 0x44 $sequence_1 = { 3334c5f3a94700 8bc2 c1e810 0fb6c0 0fb688c8a94500 8bc2 } // n = 6, score = 100 // 3334c5f3a94700 | xor esi, dword ptr [eax*8 + 0x47a9f3] // 8bc2 | mov eax, edx // c1e810 | shr eax, 0x10 // 0fb6c0 | movzx eax, al // 0fb688c8a94500 | movzx ecx, byte ptr [eax + 0x45a9c8] // 8bc2 | mov eax, edx $sequence_2 = { 33c8 8bc6 c1c806 33c8 8b442424 33442428 } // n = 6, score = 100 // 33c8 | xor ecx, eax // 8bc6 | mov eax, esi // c1c806 | ror eax, 6 // 33c8 | xor ecx, eax // 8b442424 | mov eax, dword ptr [esp + 0x24] // 33442428 | xor eax, dword ptr [esp + 0x28] $sequence_3 = { 53 8bd9 895c2404 57 c703???????? 83f808 } // n = 6, score = 100 // 53 | push ebx // 8bd9 | mov ebx, ecx // 895c2404 | mov dword ptr [esp + 4], ebx // 57 | push edi // c703???????? | // 83f808 | cmp eax, 8 $sequence_4 = { 8d45b0 50 e8???????? 83c404 ff7768 8d4dc8 } // n = 6, score = 100 // 8d45b0 | lea eax, [ebp - 0x50] // 50 | push eax // e8???????? | // 83c404 | add esp, 4 // ff7768 | push dword ptr [edi + 0x68] // 8d4dc8 | lea ecx, [ebp - 0x38] $sequence_5 = { 80f939 0f8f9a050000 0fbe46ff ff348508ad4500 } // n = 4, score = 100 // 80f939 | cmp cl, 0x39 // 0f8f9a050000 | jg 0x5a0 // 0fbe46ff | movsx eax, byte ptr [esi - 1] // ff348508ad4500 | push dword ptr [eax*4 + 0x45ad08] $sequence_6 = { 8955b8 894db0 8975b4 85c0 7514 68???????? } // n = 6, score = 100 // 8955b8 | mov dword ptr [ebp - 0x48], edx // 894db0 | mov dword ptr [ebp - 0x50], ecx // 8975b4 | mov dword ptr [ebp - 0x4c], esi // 85c0 | test eax, eax // 7514 | jne 0x16 // 68???????? | $sequence_7 = { 83c30c c645fc01 817b0455555505 8b3b 0f8493000000 8b4704 8945e8 } // n = 7, score = 100 // 83c30c | add ebx, 0xc // c645fc01 | mov byte ptr [ebp - 4], 1 // 817b0455555505 | cmp dword ptr [ebx + 4], 0x5555555 // 8b3b | mov edi, dword ptr [ebx] // 0f8493000000 | je 0x99 // 8b4704 | mov eax, dword ptr [edi + 4] // 8945e8 | mov dword ptr [ebp - 0x18], eax $sequence_8 = { 8b7508 6a0a 50 8d4590 898d78ffffff 50 c7458c00000000 } // n = 7, score = 100 // 8b7508 | mov esi, dword ptr [ebp + 8] // 6a0a | push 0xa // 50 | push eax // 8d4590 | lea eax, [ebp - 0x70] // 898d78ffffff | mov dword ptr [ebp - 0x88], ecx // 50 | push eax // c7458c00000000 | mov dword ptr [ebp - 0x74], 0 $sequence_9 = { 660fdbd9 660fdbe1 f30f7ef6 0f28cd 660fdbf2 b802000000 0f28542440 } // n = 7, score = 100 // 660fdbd9 | pand xmm3, xmm1 // 660fdbe1 | pand xmm4, xmm1 // f30f7ef6 | movq xmm6, xmm6 // 0f28cd | movaps xmm1, xmm5 // 660fdbf2 | pand xmm6, xmm2 // b802000000 | mov eax, 2 // 0f28542440 | movaps xmm2, xmmword ptr [esp + 0x40] condition: 7 of them and filesize < 1068032 }
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