Actor(s): APT37
Malware family used to deliver follow up payloads, variants using Microsoft Graph API and Google Web Apps have been observed.
rule win_bluelight_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.bluelight." 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.bluelight" 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 = { ff771c ff15???????? ff771c 8b7714 ff15???????? 5f 8bc6 } // n = 7, score = 100 // ff771c | push dword ptr [edi + 0x1c] // ff15???????? | // ff771c | push dword ptr [edi + 0x1c] // 8b7714 | mov esi, dword ptr [edi + 0x14] // ff15???????? | // 5f | pop edi // 8bc6 | mov eax, esi $sequence_1 = { 884dc7 8955d0 81faa7000000 0f87a8410000 ff249526044300 6b4b0428 6a04 } // n = 7, score = 100 // 884dc7 | mov byte ptr [ebp - 0x39], cl // 8955d0 | mov dword ptr [ebp - 0x30], edx // 81faa7000000 | cmp edx, 0xa7 // 0f87a8410000 | ja 0x41ae // ff249526044300 | jmp dword ptr [edx*4 + 0x430426] // 6b4b0428 | imul ecx, dword ptr [ebx + 4], 0x28 // 6a04 | push 4 $sequence_2 = { 85db 740f ff7760 53 ff7764 e8???????? 83c40c } // n = 7, score = 100 // 85db | test ebx, ebx // 740f | je 0x11 // ff7760 | push dword ptr [edi + 0x60] // 53 | push ebx // ff7764 | push dword ptr [edi + 0x64] // e8???????? | // 83c40c | add esp, 0xc $sequence_3 = { eb0c 8b4508 8907 c7450800000000 8b4518 894710 8b4520 } // n = 7, score = 100 // eb0c | jmp 0xe // 8b4508 | mov eax, dword ptr [ebp + 8] // 8907 | mov dword ptr [edi], eax // c7450800000000 | mov dword ptr [ebp + 8], 0 // 8b4518 | mov eax, dword ptr [ebp + 0x18] // 894710 | mov dword ptr [edi + 0x10], eax // 8b4520 | mov eax, dword ptr [ebp + 0x20] $sequence_4 = { f64605c0 7415 8d442420 68???????? 50 e8???????? ff44241c } // n = 7, score = 100 // f64605c0 | test byte ptr [esi + 5], 0xc0 // 7415 | je 0x17 // 8d442420 | lea eax, [esp + 0x20] // 68???????? | // 50 | push eax // e8???????? | // ff44241c | inc dword ptr [esp + 0x1c] $sequence_5 = { e8???????? 8d4d8c 894314 e8???????? 8d4d9c e8???????? 8d4d94 } // n = 7, score = 100 // e8???????? | // 8d4d8c | lea ecx, [ebp - 0x74] // 894314 | mov dword ptr [ebx + 0x14], eax // e8???????? | // 8d4d9c | lea ecx, [ebp - 0x64] // e8???????? | // 8d4d94 | lea ecx, [ebp - 0x6c] $sequence_6 = { e8???????? b8???????? e9???????? 8d8d60feffff e9???????? 8d4da8 e9???????? } // n = 7, score = 100 // e8???????? | // b8???????? | // e9???????? | // 8d8d60feffff | lea ecx, [ebp - 0x1a0] // e9???????? | // 8d4da8 | lea ecx, [ebp - 0x58] // e9???????? | $sequence_7 = { ff761c 50 e8???????? 83c410 8d4510 50 ff750c } // n = 7, score = 100 // ff761c | push dword ptr [esi + 0x1c] // 50 | push eax // e8???????? | // 83c410 | add esp, 0x10 // 8d4510 | lea eax, [ebp + 0x10] // 50 | push eax // ff750c | push dword ptr [ebp + 0xc] $sequence_8 = { 8b45d4 3bde 7507 8bc8 e8???????? 8a4d9f 33db } // n = 7, score = 100 // 8b45d4 | mov eax, dword ptr [ebp - 0x2c] // 3bde | cmp ebx, esi // 7507 | jne 9 // 8bc8 | mov ecx, eax // e8???????? | // 8a4d9f | mov cl, byte ptr [ebp - 0x61] // 33db | xor ebx, ebx $sequence_9 = { ff7304 8b4d0c ff73ec 6a2d 5a e8???????? 8943ec } // n = 7, score = 100 // ff7304 | push dword ptr [ebx + 4] // 8b4d0c | mov ecx, dword ptr [ebp + 0xc] // ff73ec | push dword ptr [ebx - 0x14] // 6a2d | push 0x2d // 5a | pop edx // e8???????? | // 8943ec | mov dword ptr [ebx - 0x14], eax condition: 7 of them and filesize < 2191360 }
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