Avast found this unidentified RAT, which abuses a code-signing certificate by the Philippine Navy. It is statically linked against OpenSSL 1.1.1g.
rule win_unidentified_091_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.unidentified_091." 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_091" 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 = { 81e1ff00ff00 0bd1 895618 418b481c 8bd1 c1ca08 c1c108 } // n = 7, score = 100 // 81e1ff00ff00 | shr edx, 1 // 0bd1 | lea eax, [edx + edx*2] // 895618 | inc esp // 418b481c | sub ebx, eax // 8bd1 | inc esp // c1ca08 | add ebx, ebx // c1c108 | inc ebx $sequence_1 = { c0e904 8885f8000000 888df9000000 0fb64a1d 0fb6c1 c0e904 240f } // n = 7, score = 100 // c0e904 | cmp eax, ebp // 8885f8000000 | je 0x120b // 888df9000000 | inc ecx // 0fb64a1d | mov ecx, eax // 0fb6c1 | dec eax // c0e904 | add ecx, ecx // 240f | inc esp $sequence_2 = { e8???????? 85c0 743c 48ffc3 483b5c2430 72c4 488bcf } // n = 7, score = 100 // e8???????? | // 85c0 | mov ecx, dword ptr [esp + 0x30] // 743c | dec eax // 48ffc3 | test ecx, ecx // 483b5c2430 | je 0x175 // 72c4 | dec ebp // 488bcf | test eax, eax $sequence_3 = { 8b442448 418bd1 4133d2 c1ca10 03fa 893c24 448bc7 } // n = 7, score = 100 // 8b442448 | je 0x19f4 // 418bd1 | mov eax, dword ptr [esp + 0x48] // 4133d2 | dec eax // c1ca10 | lea edx, [0xdb8bf] // 03fa | inc esp // 893c24 | mov eax, esi // 448bc7 | inc ebp $sequence_4 = { c1cd02 c1e718 418bc0 c1c005 4103c2 4489642418 03d0 } // n = 7, score = 100 // c1cd02 | dec eax // c1e718 | lea ecx, [0x111101] // 418bc0 | dec esp // c1c005 | cmp ebx, ecx // 4103c2 | jl 0xfffff672 // 4489642418 | dec eax // 03d0 | mov ecx, dword ptr [esp + 0x110] $sequence_5 = { 85c0 0f8eee000000 488d0d49421600 48894d00 48215508 48215510 ffc0 } // n = 7, score = 100 // 85c0 | je 0xa62 // 0f8eee000000 | dec esp // 488d0d49421600 | mov dword ptr [esp + 0x20], esp // 48894d00 | dec esp // 48215508 | lea ecx, [ebp - 0x78] // 48215510 | inc ebp // ffc0 | mov eax, edi $sequence_6 = { e8???????? 488bd3 488bcf 4c8bf0 8b30 c70000000000 e8???????? } // n = 7, score = 100 // e8???????? | // 488bd3 | dec eax // 488bcf | cmp eax, 4 // 4c8bf0 | jb 0x9ea // 8b30 | inc esp // c70000000000 | mov esi, ecx // e8???????? | $sequence_7 = { f30f58d0 0f57c0 0fc6d200 0f51ca 410fc2d304 0fc2c104 0f5ed9 } // n = 7, score = 100 // f30f58d0 | movups xmmword ptr [ebp - 0x19], xmm1 // 0f57c0 | movups xmm1, xmmword ptr [edx + 0x30] // 0fc6d200 | inc esp // 0f51ca | mov edx, dword ptr [ebp - 0x11] // 410fc2d304 | inc esp // 0fc2c104 | mov ecx, dword ptr [ebp - 0x15] // 0f5ed9 | inc esp $sequence_8 = { 4c894507 48894d0f e9???????? c74424285a0a0000 ba50000000 4c89542420 41b966010000 } // n = 7, score = 100 // 4c894507 | inc ecx // 48894d0f | mov eax, 0x200 // e9???????? | // c74424285a0a0000 | dec eax // ba50000000 | lea ecx, [ebp + 0x3e0] // 4c89542420 | jne 0x11db // 41b966010000 | dec esp $sequence_9 = { c784248000000001000000 eb32 c7442420f6010000 baa6000000 4c8d0db8a71100 b906000000 448d42fc } // n = 7, score = 100 // c784248000000001000000 | dec eax // eb32 | lea ecx, [0x1942a5] // c7442420f6010000 | dec esp // baa6000000 | mov eax, edi // 4c8d0db8a71100 | dec eax // b906000000 | test eax, eax // 448d42fc | dec eax condition: 7 of them and filesize < 5777408 }
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