Unidentified downloader, possibly related to KONNI.
rule win_unidentified_070_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.unidentified_070." 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_070" malpedia_rule_date = "20231130" malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351" malpedia_version = "20230808" 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 = { 6a04 50 ff15???????? 8945fc 85c0 } // n = 5, score = 300 // 6a04 | push 4 // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax // 85c0 | test eax, eax $sequence_1 = { 6a00 6a00 6a04 50 ff15???????? 8945fc 85c0 } // n = 7, score = 300 // 6a00 | push 0 // 6a00 | push 0 // 6a04 | push 4 // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax // 85c0 | test eax, eax $sequence_2 = { 33c0 c20400 3b0d???????? 7502 } // n = 4, score = 300 // 33c0 | xor eax, eax // c20400 | ret 4 // 3b0d???????? | // 7502 | jne 4 $sequence_3 = { 6a00 6a04 50 ff15???????? 8945fc } // n = 5, score = 300 // 6a00 | push 0 // 6a04 | push 4 // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax $sequence_4 = { 6a00 6a04 50 ff15???????? 8945fc 85c0 } // n = 6, score = 300 // 6a00 | push 0 // 6a04 | push 4 // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax // 85c0 | test eax, eax $sequence_5 = { 6a00 6a00 6a00 6a04 50 ff15???????? 8945fc } // n = 7, score = 300 // 6a00 | push 0 // 6a00 | push 0 // 6a00 | push 0 // 6a04 | push 4 // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax $sequence_6 = { 6a00 6a00 6a04 50 ff15???????? 8945fc } // n = 6, score = 300 // 6a00 | push 0 // 6a00 | push 0 // 6a04 | push 4 // 50 | push eax // ff15???????? | // 8945fc | mov dword ptr [ebp - 4], eax $sequence_7 = { 6a00 8d45f4 50 ff75fc 57 56 } // n = 6, score = 200 // 6a00 | push 0 // 8d45f4 | lea eax, [ebp - 0xc] // 50 | push eax // ff75fc | push dword ptr [ebp - 4] // 57 | push edi // 56 | push esi $sequence_8 = { 8bf9 c78424cc00000000000000 66c78424d00000000010 e8???????? 83c40c 8d442424 50 } // n = 7, score = 200 // 8bf9 | mov edi, ecx // c78424cc00000000000000 | mov dword ptr [esp + 0xcc], 0 // 66c78424d00000000010 | mov word ptr [esp + 0xd0], 0x1000 // e8???????? | // 83c40c | add esp, 0xc // 8d442424 | lea eax, [esp + 0x24] // 50 | push eax $sequence_9 = { 6a00 56 ff15???????? 8945f8 85c0 0f8493000000 6a00 } // n = 7, score = 200 // 6a00 | push 0 // 56 | push esi // ff15???????? | // 8945f8 | mov dword ptr [ebp - 8], eax // 85c0 | test eax, eax // 0f8493000000 | je 0x99 // 6a00 | push 0 condition: 7 of them and filesize < 90112 }
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