Actor(s): Anunak, TA505
TinyMet is a meterpreter stager.
rule win_tinymet_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-07-11" 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 = "20230705" malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41" malpedia_version = "20230715" 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 = { 741d 48 7416 68???????? e8???????? c70424???????? e9???????? } // n = 7, score = 100 // 741d | je 0x1f // 48 | dec eax // 7416 | je 0x18 // 68???????? | // e8???????? | // c70424???????? | // e9???????? | $sequence_1 = { 8bec ff15???????? 50 ff7508 } // n = 4, score = 100 // 8bec | mov ebp, esp // ff15???????? | // 50 | push eax // ff7508 | push dword ptr [ebp + 8] $sequence_2 = { 57 885df0 895df1 885de8 895de9 885ded } // n = 6, score = 100 // 57 | push edi // 885df0 | mov byte ptr [ebp - 0x10], bl // 895df1 | mov dword ptr [ebp - 0xf], ebx // 885de8 | mov byte ptr [ebp - 0x18], bl // 895de9 | mov dword ptr [ebp - 0x17], ebx // 885ded | mov byte ptr [ebp - 0x13], bl $sequence_3 = { 6800100000 83c005 50 6a00 ff15???????? a3???????? 6a04 } // n = 7, score = 100 // 6800100000 | push 0x1000 // 83c005 | add eax, 5 // 50 | push eax // 6a00 | push 0 // ff15???????? | // a3???????? | // 6a04 | push 4 $sequence_4 = { 75df 8bc7 5f 5e 5b 8be5 5d } // n = 7, score = 100 // 75df | jne 0xffffffe1 // 8bc7 | mov eax, edi // 5f | pop edi // 5e | pop esi // 5b | pop ebx // 8be5 | mov esp, ebp // 5d | pop ebp $sequence_5 = { 668907 e8???????? 83c702 a3???????? 6a5f 57 } // n = 6, score = 100 // 668907 | mov word ptr [edi], ax // e8???????? | // 83c702 | add edi, 2 // a3???????? | // 6a5f | push 0x5f // 57 | push edi $sequence_6 = { ff35???????? ff35???????? e8???????? 83c40c a3???????? ffd0 6a00 } // n = 7, score = 100 // ff35???????? | // ff35???????? | // e8???????? | // 83c40c | add esp, 0xc // a3???????? | // ffd0 | call eax // 6a00 | push 0 $sequence_7 = { 8d45e8 50 e8???????? 83c410 b80033a084 } // n = 5, score = 100 // 8d45e8 | lea eax, [ebp - 0x18] // 50 | push eax // e8???????? | // 83c410 | add esp, 0x10 // b80033a084 | mov eax, 0x84a03300 condition: 7 of them and filesize < 57344 }
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