Actor(s): Anunak, TA505
TinyMet is a meterpreter stager.
rule win_tinymet_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-03-29" 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 = "20230328" malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d" malpedia_version = "20230407" 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 = { eb03 83c602 6a2e 56 e8???????? 33c9 6a5f } // n = 7, score = 100 // eb03 | jmp 5 // 83c602 | add esi, 2 // 6a2e | push 0x2e // 56 | push esi // e8???????? | // 33c9 | xor ecx, ecx // 6a5f | push 0x5f $sequence_1 = { 6a5f 56 668908 e8???????? 8bf8 } // n = 5, score = 100 // 6a5f | push 0x5f // 56 | push esi // 668908 | mov word ptr [eax], cx // e8???????? | // 8bf8 | mov edi, eax $sequence_2 = { 751b 68???????? e9???????? ff15???????? 85c0 7407 68???????? } // n = 7, score = 100 // 751b | jne 0x1d // 68???????? | // e9???????? | // ff15???????? | // 85c0 | test eax, eax // 7407 | je 9 // 68???????? | $sequence_3 = { a3???????? 6a04 c600bf 8d45fc 50 } // n = 5, score = 100 // a3???????? | // 6a04 | push 4 // c600bf | mov byte ptr [eax], 0xbf // 8d45fc | lea eax, [ebp - 4] // 50 | push eax $sequence_4 = { 6a02 894df0 59 53 6a01 51 66a3???????? } // n = 7, score = 100 // 6a02 | push 2 // 894df0 | mov dword ptr [ebp - 0x10], ecx // 59 | pop ecx // 53 | push ebx // 6a01 | push 1 // 51 | push ecx // 66a3???????? | $sequence_5 = { 51 66a3???????? 66894dec 668945ee ff15???????? } // n = 5, score = 100 // 51 | push ecx // 66a3???????? | // 66894dec | mov word ptr [ebp - 0x14], cx // 668945ee | mov word ptr [ebp - 0x12], ax // ff15???????? | $sequence_6 = { 7416 6a04 8d45fc c745fc80330000 50 6a1f } // n = 6, score = 100 // 7416 | je 0x18 // 6a04 | push 4 // 8d45fc | lea eax, [ebp - 4] // c745fc80330000 | mov dword ptr [ebp - 4], 0x3380 // 50 | push eax // 6a1f | push 0x1f $sequence_7 = { 7412 0fbe043e 03d8 46 } // n = 4, score = 100 // 7412 | je 0x14 // 0fbe043e | movsx eax, byte ptr [esi + edi] // 03d8 | add ebx, eax // 46 | inc esi condition: 7 of them and filesize < 57344 }
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