Actor(s): Tiny Spider
There is no description at this point.
rule win_tinyloader_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-03-28" version = "1" description = "Detects win.tinyloader." 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.tinyloader" 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 = { 8b4500 83c00c ffd0 31db } // n = 4, score = 100 // 8b4500 | mov eax, dword ptr [ebp] // 83c00c | add eax, 0xc // ffd0 | call eax // 31db | xor ebx, ebx $sequence_1 = { 68???????? ff15???????? 8d3500304000 89c7 } // n = 4, score = 100 // 68???????? | // ff15???????? | // 8d3500304000 | lea esi, [0x403000] // 89c7 | mov edi, eax $sequence_2 = { ff15???????? e8???????? 53 68656c6c45 7865 637574 6541 } // n = 7, score = 100 // ff15???????? | // e8???????? | // 53 | push ebx // 68656c6c45 | push 0x456c6c65 // 7865 | js 0x67 // 637574 | arpl word ptr [ebp + 0x74], si // 6541 | inc ecx $sequence_3 = { 8938 90 81fb04030000 730d 90 } // n = 5, score = 100 // 8938 | mov dword ptr [eax], edi // 90 | nop // 81fb04030000 | cmp ebx, 0x304 // 730d | jae 0xf // 90 | nop $sequence_4 = { 8b1d???????? 90 895838 90 89c6 90 0500400100 } // n = 7, score = 100 // 8b1d???????? | // 90 | nop // 895838 | mov dword ptr [eax + 0x38], ebx // 90 | nop // 89c6 | mov esi, eax // 90 | nop // 0500400100 | add eax, 0x14000 $sequence_5 = { 7505 e9???????? 8b4500 83c008 c70000000000 } // n = 5, score = 100 // 7505 | jne 7 // e9???????? | // 8b4500 | mov eax, dword ptr [ebp] // 83c008 | add eax, 8 // c70000000000 | mov dword ptr [eax], 0 $sequence_6 = { 8b03 8b5d00 66894308 6a10 ffb5a8050000 ffb5b8050000 } // n = 6, score = 100 // 8b03 | mov eax, dword ptr [ebx] // 8b5d00 | mov ebx, dword ptr [ebp] // 66894308 | mov word ptr [ebx + 8], ax // 6a10 | push 0x10 // ffb5a8050000 | push dword ptr [ebp + 0x5a8] // ffb5b8050000 | push dword ptr [ebp + 0x5b8] $sequence_7 = { 637574 6541 0050ff 15???????? c705????????00010000 } // n = 5, score = 100 // 637574 | arpl word ptr [ebp + 0x74], si // 6541 | inc ecx // 0050ff | add byte ptr [eax - 1], dl // 15???????? | // c705????????00010000 | $sequence_8 = { 6a00 6800040000 53 ffb5b8050000 ff15???????? } // n = 5, score = 100 // 6a00 | push 0 // 6800040000 | push 0x400 // 53 | push ebx // ffb5b8050000 | push dword ptr [ebp + 0x5b8] // ff15???????? | $sequence_9 = { ff15???????? 8b9da8050000 66894302 66c7030200 e8???????? } // n = 5, score = 100 // ff15???????? | // 8b9da8050000 | mov ebx, dword ptr [ebp + 0x5a8] // 66894302 | mov word ptr [ebx + 2], ax // 66c7030200 | mov word ptr [ebx], 2 // e8???????? | $sequence_10 = { 8985b0020000 83bdb002000000 7502 eb1f ff15???????? } // n = 5, score = 100 // 8985b0020000 | mov dword ptr [ebp + 0x2b0], eax // 83bdb002000000 | cmp dword ptr [ebp + 0x2b0], 0 // 7502 | jne 4 // eb1f | jmp 0x21 // ff15???????? | $sequence_11 = { 8b5500 01da 83c20c 310a 3b8558080000 } // n = 5, score = 100 // 8b5500 | mov edx, dword ptr [ebp] // 01da | add edx, ebx // 83c20c | add edx, 0xc // 310a | xor dword ptr [edx], ecx // 3b8558080000 | cmp eax, dword ptr [ebp + 0x858] $sequence_12 = { 0500200000 8985a8050000 0500080000 894508 } // n = 4, score = 100 // 0500200000 | add eax, 0x2000 // 8985a8050000 | mov dword ptr [ebp + 0x5a8], eax // 0500080000 | add eax, 0x800 // 894508 | mov dword ptr [ebp + 8], eax $sequence_13 = { ff15???????? 90 8b1d???????? 90 8998f8070000 } // n = 5, score = 100 // ff15???????? | // 90 | nop // 8b1d???????? | // 90 | nop // 8998f8070000 | mov dword ptr [eax + 0x7f8], ebx $sequence_14 = { 3108 90 813890909090 740e } // n = 4, score = 100 // 3108 | xor dword ptr [eax], ecx // 90 | nop // 813890909090 | cmp dword ptr [eax], 0x90909090 // 740e | je 0x10 $sequence_15 = { 83fb00 7509 90 3108 } // n = 4, score = 100 // 83fb00 | cmp ebx, 0 // 7509 | jne 0xb // 90 | nop // 3108 | xor dword ptr [eax], ecx condition: 7 of them and filesize < 40960 }
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