Actor(s): Lazarus Group
There is no description at this point.
rule win_bravonc_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.bravonc." 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.bravonc" malpedia_rule_date = "20231130" malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351" malpedia_version = "20230808" 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 = { 0f8c05040000 8b06 3b7804 0f8dfa030000 395e04 7407 50 } // n = 7, score = 100 // 0f8c05040000 | jl 0x40b // 8b06 | mov eax, dword ptr [esi] // 3b7804 | cmp edi, dword ptr [eax + 4] // 0f8dfa030000 | jge 0x400 // 395e04 | cmp dword ptr [esi + 4], ebx // 7407 | je 9 // 50 | push eax $sequence_1 = { 5b c3 55 8bec 53 33db 395d0c } // n = 7, score = 100 // 5b | pop ebx // c3 | ret // 55 | push ebp // 8bec | mov ebp, esp // 53 | push ebx // 33db | xor ebx, ebx // 395d0c | cmp dword ptr [ebp + 0xc], ebx $sequence_2 = { 57 ff75ec 334dec 030a 034df0 8d8401d6c162ca 8945f0 } // n = 7, score = 100 // 57 | push edi // ff75ec | push dword ptr [ebp - 0x14] // 334dec | xor ecx, dword ptr [ebp - 0x14] // 030a | add ecx, dword ptr [edx] // 034df0 | add ecx, dword ptr [ebp - 0x10] // 8d8401d6c162ca | lea eax, [ecx + eax - 0x359d3e2a] // 8945f0 | mov dword ptr [ebp - 0x10], eax $sequence_3 = { 8907 8b45f4 2bfb 59 59 8907 8b45fc } // n = 7, score = 100 // 8907 | mov dword ptr [edi], eax // 8b45f4 | mov eax, dword ptr [ebp - 0xc] // 2bfb | sub edi, ebx // 59 | pop ecx // 59 | pop ecx // 8907 | mov dword ptr [edi], eax // 8b45fc | mov eax, dword ptr [ebp - 4] $sequence_4 = { 83c430 8bce 53 56 e8???????? 5f 5e } // n = 7, score = 100 // 83c430 | add esp, 0x30 // 8bce | mov ecx, esi // 53 | push ebx // 56 | push esi // e8???????? | // 5f | pop edi // 5e | pop esi $sequence_5 = { e8???????? 8b0e 030f c1e104 2bc1 eb08 8d4de0 } // n = 7, score = 100 // e8???????? | // 8b0e | mov ecx, dword ptr [esi] // 030f | add ecx, dword ptr [edi] // c1e104 | shl ecx, 4 // 2bc1 | sub eax, ecx // eb08 | jmp 0xa // 8d4de0 | lea ecx, [ebp - 0x20] $sequence_6 = { ff75f0 e8???????? 8b4df8 83c440 334dec 57 } // n = 6, score = 100 // ff75f0 | push dword ptr [ebp - 0x10] // e8???????? | // 8b4df8 | mov ecx, dword ptr [ebp - 8] // 83c440 | add esp, 0x40 // 334dec | xor ecx, dword ptr [ebp - 0x14] // 57 | push edi $sequence_7 = { 335dfc 3175fc 83c118 ff4df0 8bf2 8b55fc 8955f8 } // n = 7, score = 100 // 335dfc | xor ebx, dword ptr [ebp - 4] // 3175fc | xor dword ptr [ebp - 4], esi // 83c118 | add ecx, 0x18 // ff4df0 | dec dword ptr [ebp - 0x10] // 8bf2 | mov esi, edx // 8b55fc | mov edx, dword ptr [ebp - 4] // 8955f8 | mov dword ptr [ebp - 8], edx $sequence_8 = { 83450c08 ebd2 d36d08 8b0c8590b24000 234d08 014df0 8bc8 } // n = 7, score = 100 // 83450c08 | add dword ptr [ebp + 0xc], 8 // ebd2 | jmp 0xffffffd4 // d36d08 | shr dword ptr [ebp + 8], cl // 8b0c8590b24000 | mov ecx, dword ptr [eax*4 + 0x40b290] // 234d08 | and ecx, dword ptr [ebp + 8] // 014df0 | add dword ptr [ebp - 0x10], ecx // 8bc8 | mov ecx, eax $sequence_9 = { 03f3 2bfb 03f3 890f } // n = 4, score = 100 // 03f3 | add esi, ebx // 2bfb | sub edi, ebx // 03f3 | add esi, ebx // 890f | mov dword ptr [edi], ecx condition: 7 of them and filesize < 131072 }
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