According to Volexity, a loader observed to be used with multiple malware families, among them LIGHTSPY.
rule win_bh_a006_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.bh_a006." 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.bh_a006" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" 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 = { 8bca 2b08 03cb 8930 } // n = 4, score = 100 // 8bca | mov ecx, edx // 2b08 | sub ecx, dword ptr [eax] // 03cb | add ecx, ebx // 8930 | mov dword ptr [eax], esi $sequence_1 = { 6683bdecdfffff00 8dbdecdfffff 7436 57 } // n = 4, score = 100 // 6683bdecdfffff00 | cmp word ptr [ebp - 0x2014], 0 // 8dbdecdfffff | lea edi, [ebp - 0x2014] // 7436 | je 0x38 // 57 | push edi $sequence_2 = { 88041a 42 884517 8955f4 e9???????? 2bf0 } // n = 6, score = 100 // 88041a | mov byte ptr [edx + ebx], al // 42 | inc edx // 884517 | mov byte ptr [ebp + 0x17], al // 8955f4 | mov dword ptr [ebp - 0xc], edx // e9???????? | // 2bf0 | sub esi, eax $sequence_3 = { 85ff 7472 8d45fc 50 } // n = 4, score = 100 // 85ff | test edi, edi // 7472 | je 0x74 // 8d45fc | lea eax, [ebp - 4] // 50 | push eax $sequence_4 = { 8b95e4deffff 59 83e201 c1e202 6a04 59 } // n = 6, score = 100 // 8b95e4deffff | mov edx, dword ptr [ebp - 0x211c] // 59 | pop ecx // 83e201 | and edx, 1 // c1e202 | shl edx, 2 // 6a04 | push 4 // 59 | pop ecx $sequence_5 = { 8985d4ddffff 8985d8ddffff 8985dcddffff 8945fc } // n = 4, score = 100 // 8985d4ddffff | mov dword ptr [ebp - 0x222c], eax // 8985d8ddffff | mov dword ptr [ebp - 0x2228], eax // 8985dcddffff | mov dword ptr [ebp - 0x2224], eax // 8945fc | mov dword ptr [ebp - 4], eax $sequence_6 = { 898de4deffff 3bcb 7cbb 8bb5d8deffff 33db 8b85d0deffff 56 } // n = 7, score = 100 // 898de4deffff | mov dword ptr [ebp - 0x211c], ecx // 3bcb | cmp ecx, ebx // 7cbb | jl 0xffffffbd // 8bb5d8deffff | mov esi, dword ptr [ebp - 0x2128] // 33db | xor ebx, ebx // 8b85d0deffff | mov eax, dword ptr [ebp - 0x2130] // 56 | push esi $sequence_7 = { 50 68???????? 8d85b8f5ffff 50 e8???????? 85c0 7922 } // n = 7, score = 100 // 50 | push eax // 68???????? | // 8d85b8f5ffff | lea eax, [ebp - 0xa48] // 50 | push eax // e8???????? | // 85c0 | test eax, eax // 7922 | jns 0x24 condition: 7 of them and filesize < 430080 }
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