The Chinese threat actor has used a custom backdoor dubbed "Scieron" over years in several campaigns according to SentinelLABS.
rule win_scieron_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-07-11" version = "1" description = "Detects win.scieron." 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.scieron" 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 = { 5e c9 c3 8b85dcfdffff ebf5 } // n = 5, score = 100 // 5e | pop esi // c9 | leave // c3 | ret // 8b85dcfdffff | mov eax, dword ptr [ebp - 0x224] // ebf5 | jmp 0xfffffff7 $sequence_1 = { 8b442410 69c050020000 05???????? 50 ff74241c ff15???????? } // n = 6, score = 100 // 8b442410 | mov eax, dword ptr [esp + 0x10] // 69c050020000 | imul eax, eax, 0x250 // 05???????? | // 50 | push eax // ff74241c | push dword ptr [esp + 0x1c] // ff15???????? | $sequence_2 = { 685cee0000 8935???????? ff15???????? 68???????? } // n = 4, score = 100 // 685cee0000 | push 0xee5c // 8935???????? | // ff15???????? | // 68???????? | $sequence_3 = { e8???????? 8bf8 83c410 85ff 7432 } // n = 5, score = 100 // e8???????? | // 8bf8 | mov edi, eax // 83c410 | add esp, 0x10 // 85ff | test edi, edi // 7432 | je 0x34 $sequence_4 = { 8bf8 56 83ffff 754d ff15???????? } // n = 5, score = 100 // 8bf8 | mov edi, eax // 56 | push esi // 83ffff | cmp edi, -1 // 754d | jne 0x4f // ff15???????? | $sequence_5 = { eb65 8b4734 50 894574 8d472c 50 } // n = 6, score = 100 // eb65 | jmp 0x67 // 8b4734 | mov eax, dword ptr [edi + 0x34] // 50 | push eax // 894574 | mov dword ptr [ebp + 0x74], eax // 8d472c | lea eax, [edi + 0x2c] // 50 | push eax $sequence_6 = { 6a40 ff15???????? 8903 85c0 742e 0fb74df6 51 } // n = 7, score = 100 // 6a40 | push 0x40 // ff15???????? | // 8903 | mov dword ptr [ebx], eax // 85c0 | test eax, eax // 742e | je 0x30 // 0fb74df6 | movzx ecx, word ptr [ebp - 0xa] // 51 | push ecx $sequence_7 = { e9???????? 53 55 55 56 } // n = 5, score = 100 // e9???????? | // 53 | push ebx // 55 | push ebp // 55 | push ebp // 56 | push esi $sequence_8 = { 53 6a40 ffd7 85c0 7417 6a00 56 } // n = 7, score = 100 // 53 | push ebx // 6a40 | push 0x40 // ffd7 | call edi // 85c0 | test eax, eax // 7417 | je 0x19 // 6a00 | push 0 // 56 | push esi $sequence_9 = { 83a61c02000000 33c0 40 5f 5d } // n = 5, score = 100 // 83a61c02000000 | and dword ptr [esi + 0x21c], 0 // 33c0 | xor eax, eax // 40 | inc eax // 5f | pop edi // 5d | pop ebp condition: 7 of them and filesize < 100352 }
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