Actor(s): Anunak, TA505
TinyMet is a meterpreter stager.
rule win_tinymet_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.tinymet." 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.tinymet" 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 = { e9???????? 8b400c ff750c 8b00 8b00 a3???????? } // n = 6, score = 100 // e9???????? | // 8b400c | mov eax, dword ptr [eax + 0xc] // ff750c | push dword ptr [ebp + 0xc] // 8b00 | mov eax, dword ptr [eax] // 8b00 | mov eax, dword ptr [eax] // a3???????? | $sequence_1 = { 7419 a1???????? 6a00 83c005 56 } // n = 5, score = 100 // 7419 | je 0x1b // a1???????? | // 6a00 | push 0 // 83c005 | add eax, 5 // 56 | push esi $sequence_2 = { 5e 5d c3 a1???????? 56 57 6a5c } // n = 7, score = 100 // 5e | pop esi // 5d | pop ebp // c3 | ret // a1???????? | // 56 | push esi // 57 | push edi // 6a5c | push 0x5c $sequence_3 = { 85c0 0f8545010000 ff7508 ff15???????? 85c0 750a 68???????? } // n = 7, score = 100 // 85c0 | test eax, eax // 0f8545010000 | jne 0x14b // ff7508 | push dword ptr [ebp + 8] // ff15???????? | // 85c0 | test eax, eax // 750a | jne 0xc // 68???????? | $sequence_4 = { 385d10 7416 6a04 8d45fc } // n = 4, score = 100 // 385d10 | cmp byte ptr [ebp + 0x10], bl // 7416 | je 0x18 // 6a04 | push 4 // 8d45fc | lea eax, [ebp - 4] $sequence_5 = { 8d45f0 50 8d45e8 50 e8???????? 83c410 b80033a084 } // n = 7, score = 100 // 8d45f0 | lea eax, [ebp - 0x10] // 50 | push eax // 8d45e8 | lea eax, [ebp - 0x18] // 50 | push eax // e8???????? | // 83c410 | add esp, 0x10 // b80033a084 | mov eax, 0x84a03300 $sequence_6 = { a1???????? 59 50 ff35???????? } // n = 4, score = 100 // a1???????? | // 59 | pop ecx // 50 | push eax // ff35???????? | $sequence_7 = { 33c0 57 668906 e8???????? a3???????? 8d4602 50 } // n = 7, score = 100 // 33c0 | xor eax, eax // 57 | push edi // 668906 | mov word ptr [esi], ax // e8???????? | // a3???????? | // 8d4602 | lea eax, [esi + 2] // 50 | push eax condition: 7 of them and filesize < 57344 }
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