Actor(s): Pirate Panda
PcShare is a open-source backdoor which has been seen modified and used by Chinese threat actors, mainly attacking countries in South East Asia.
rule win_pcshare_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.pcshare." 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.pcshare" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" 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 = { 803c3800 75db 8b16 33c0 8a0c3a 5f 84c9 } // n = 7, score = 100 // 803c3800 | cmp byte ptr [eax + edi], 0 // 75db | jne 0xffffffdd // 8b16 | mov edx, dword ptr [esi] // 33c0 | xor eax, eax // 8a0c3a | mov cl, byte ptr [edx + edi] // 5f | pop edi // 84c9 | test cl, cl $sequence_1 = { 8db60c2c0610 6a00 50 ff36 e8???????? } // n = 5, score = 100 // 8db60c2c0610 | lea esi, [esi + 0x10062c0c] // 6a00 | push 0 // 50 | push eax // ff36 | push dword ptr [esi] // e8???????? | $sequence_2 = { 8b442450 3bc3 7425 33f6 8b0c06 } // n = 5, score = 100 // 8b442450 | mov eax, dword ptr [esp + 0x50] // 3bc3 | cmp eax, ebx // 7425 | je 0x27 // 33f6 | xor esi, esi // 8b0c06 | mov ecx, dword ptr [esi + eax] $sequence_3 = { 81e20000ffff c7401400000000 0bca 89480c 8b4c2440 8b542438 } // n = 6, score = 100 // 81e20000ffff | and edx, 0xffff0000 // c7401400000000 | mov dword ptr [eax + 0x14], 0 // 0bca | or ecx, edx // 89480c | mov dword ptr [eax + 0xc], ecx // 8b4c2440 | mov ecx, dword ptr [esp + 0x40] // 8b542438 | mov edx, dword ptr [esp + 0x38] $sequence_4 = { 8b4c242c 85c9 7510 3b5c2430 746b 43 } // n = 6, score = 100 // 8b4c242c | mov ecx, dword ptr [esp + 0x2c] // 85c9 | test ecx, ecx // 7510 | jne 0x12 // 3b5c2430 | cmp ebx, dword ptr [esp + 0x30] // 746b | je 0x6d // 43 | inc ebx $sequence_5 = { 8b01 03f8 8b5640 8b6e24 52 51 8bcc } // n = 7, score = 100 // 8b01 | mov eax, dword ptr [ecx] // 03f8 | add edi, eax // 8b5640 | mov edx, dword ptr [esi + 0x40] // 8b6e24 | mov ebp, dword ptr [esi + 0x24] // 52 | push edx // 51 | push ecx // 8bcc | mov ecx, esp $sequence_6 = { 8b5b04 03d8 c60300 8b442428 50 } // n = 5, score = 100 // 8b5b04 | mov ebx, dword ptr [ebx + 4] // 03d8 | add ebx, eax // c60300 | mov byte ptr [ebx], 0 // 8b442428 | mov eax, dword ptr [esp + 0x28] // 50 | push eax $sequence_7 = { 8d0480 8d0c80 8d048a 3d35c83301 0f8cea000000 68???????? } // n = 6, score = 100 // 8d0480 | lea eax, [eax + eax*4] // 8d0c80 | lea ecx, [eax + eax*4] // 8d048a | lea eax, [edx + ecx*4] // 3d35c83301 | cmp eax, 0x133c835 // 0f8cea000000 | jl 0xf0 // 68???????? | $sequence_8 = { 8b16 8d441a02 50 55 ff15???????? 85c0 890437 } // n = 7, score = 100 // 8b16 | mov edx, dword ptr [esi] // 8d441a02 | lea eax, [edx + ebx + 2] // 50 | push eax // 55 | push ebp // ff15???????? | // 85c0 | test eax, eax // 890437 | mov dword ptr [edi + esi], eax $sequence_9 = { 8b4548 8b4c241c 8b1408 8b442420 8b4c020c 8d44020c } // n = 6, score = 100 // 8b4548 | mov eax, dword ptr [ebp + 0x48] // 8b4c241c | mov ecx, dword ptr [esp + 0x1c] // 8b1408 | mov edx, dword ptr [eax + ecx] // 8b442420 | mov eax, dword ptr [esp + 0x20] // 8b4c020c | mov ecx, dword ptr [edx + eax + 0xc] // 8d44020c | lea eax, [edx + eax + 0xc] condition: 7 of them and filesize < 893708 }
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