A loader that has been used by multiple threat actor groups since 2015.
rule win_hui_loader_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.hui_loader." 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.hui_loader" 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 = { 68???????? 51 8bf8 ffd5 8d9424b8010000 8d842488090000 } // n = 6, score = 100 // 68???????? | // 51 | push ecx // 8bf8 | mov edi, eax // ffd5 | call ebp // 8d9424b8010000 | lea edx, [esp + 0x1b8] // 8d842488090000 | lea eax, [esp + 0x988] $sequence_1 = { ffd0 68e8030000 ffd6 8b0d???????? 51 ff15???????? 5f } // n = 7, score = 100 // ffd0 | call eax // 68e8030000 | push 0x3e8 // ffd6 | call esi // 8b0d???????? | // 51 | push ecx // ff15???????? | // 5f | pop edi $sequence_2 = { 8b1402 3bd3 7406 c70109000000 } // n = 4, score = 100 // 8b1402 | mov edx, dword ptr [edx + eax] // 3bd3 | cmp edx, ebx // 7406 | je 8 // c70109000000 | mov dword ptr [ecx], 9 $sequence_3 = { 83e01f c1f905 8d04c0 8b0c8d60e20010 8d44810c 50 } // n = 6, score = 100 // 83e01f | and eax, 0x1f // c1f905 | sar ecx, 5 // 8d04c0 | lea eax, [eax + eax*8] // 8b0c8d60e20010 | mov ecx, dword ptr [ecx*4 + 0x1000e260] // 8d44810c | lea eax, [ecx + eax*4 + 0xc] // 50 | push eax $sequence_4 = { 52 50 a3???????? ff15???????? a1???????? } // n = 5, score = 100 // 52 | push edx // 50 | push eax // a3???????? | // ff15???????? | // a1???????? | $sequence_5 = { 83c628 83f90a 7cd9 33d2 } // n = 4, score = 100 // 83c628 | add esi, 0x28 // 83f90a | cmp ecx, 0xa // 7cd9 | jl 0xffffffdb // 33d2 | xor edx, edx $sequence_6 = { 8d4a01 0338 83c004 49 75f8 42 83c628 } // n = 7, score = 100 // 8d4a01 | lea ecx, [edx + 1] // 0338 | add edi, dword ptr [eax] // 83c004 | add eax, 4 // 49 | dec ecx // 75f8 | jne 0xfffffffa // 42 | inc edx // 83c628 | add esi, 0x28 $sequence_7 = { c20400 8b15???????? 33c0 68???????? 52 } // n = 5, score = 100 // c20400 | ret 4 // 8b15???????? | // 33c0 | xor eax, eax // 68???????? | // 52 | push edx $sequence_8 = { ff15???????? a3???????? 33ff 8d4c2428 } // n = 4, score = 100 // ff15???????? | // a3???????? | // 33ff | xor edi, edi // 8d4c2428 | lea ecx, [esp + 0x28] $sequence_9 = { 7e0f 8b4efc 8b5401fc 031401 8b0e 891401 } // n = 6, score = 100 // 7e0f | jle 0x11 // 8b4efc | mov ecx, dword ptr [esi - 4] // 8b5401fc | mov edx, dword ptr [ecx + eax - 4] // 031401 | add edx, dword ptr [ecx + eax] // 8b0e | mov ecx, dword ptr [esi] // 891401 | mov dword ptr [ecx + eax], edx condition: 7 of them and filesize < 131072 }
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