Actor(s): IcePeony
According to nao_sec, this malware is an IIS backdoor.
rule win_ice_cache_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.ice_cache." 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.ice_cache" 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 = { 4156 4157 4883ec30 488b19 498be8 4c8bf2 } // n = 6, score = 100 // 4156 | je 0x822 // 4157 | dec ebp // 4883ec30 | test eax, eax // 488b19 | dec eax // 498be8 | mov esi, dword ptr [esp + 0x10] // 4c8bf2 | xor eax, eax $sequence_1 = { 488bd9 4885c0 7479 488d0d0a520200 483bc1 746d 488b83e0000000 } // n = 7, score = 100 // 488bd9 | pop ebx // 4885c0 | mov byte ptr [esi], al // 7479 | dec eax // 488d0d0a520200 | inc ebp // 483bc1 | dec eax // 746d | inc esi // 488b83e0000000 | dec eax $sequence_2 = { 33d2 498bce e8???????? 90 488d8c24080f0000 e8???????? e9???????? } // n = 7, score = 100 // 33d2 | mov ebx, dword ptr [eax] // 498bce | dec eax // e8???????? | // 90 | lea ecx, [esp + 0x1568] // 488d8c24080f0000 | dec eax // e8???????? | // e9???????? | $sequence_3 = { 0f114a10 4c894110 48c741180f000000 448801 44894220 4883c420 } // n = 6, score = 100 // 0f114a10 | test eax, eax // 4c894110 | setne bl // 48c741180f000000 | dec ecx // 448801 | cmp eax, 8 // 44894220 | jb 0x167e // 4883c420 | dec esp $sequence_4 = { 48f7d0 493bc6 0f8694000000 48897c2430 4a8d3c01 4d85f6 746d } // n = 7, score = 100 // 48f7d0 | lea edx, [0x476ee] // 493bc6 | dec eax // 0f8694000000 | lea ecx, [esp + 0x1608] // 48897c2430 | nop // 4a8d3c01 | nop // 4d85f6 | dec eax // 746d | lea edx, [0x477fe] $sequence_5 = { 488b542448 488d4c2448 e8???????? e8???????? e8???????? 0fb6c3 488b4c2468 } // n = 7, score = 100 // 488b542448 | cmp dword ptr [eax], edi // 488d4c2448 | jne 0xc93 // e8???????? | // e8???????? | // e8???????? | // 0fb6c3 | dec esp // 488b4c2468 | mov dword ptr [edx], eax $sequence_6 = { 744c 0fb618 48ffc0 48894710 83fbff 7440 } // n = 6, score = 100 // 744c | dec esp // 0fb618 | mov esi, edx // 48ffc0 | dec eax // 48894710 | mov ebx, ecx // 83fbff | inc ebp // 7440 | xor ebp, ebp $sequence_7 = { 74e8 488bd8 4889442470 493bdf 7410 488d5320 498bce } // n = 7, score = 100 // 74e8 | dec eax // 488bd8 | lea ecx, [ebp + 7] // 4889442470 | inc esp // 493bdf | movzx ecx, word ptr [esp + 0x1158] // 7410 | dec eax // 488d5320 | lea edx, [0x48016] // 498bce | dec ecx $sequence_8 = { 7536 4c8bc7 488d1502700300 660f1f440000 0fb702 663901 } // n = 6, score = 100 // 7536 | mov eax, dword ptr [ebx] // 4c8bc7 | dec eax // 488d1502700300 | arpl word ptr [eax], cx // 660f1f440000 | dec eax // 0fb702 | mov edx, ecx // 663901 | dec eax $sequence_9 = { 418bf0 4c8d0d0f870100 8bda 4c8d05fe860100 } // n = 4, score = 100 // 418bf0 | lea edx, [0xfffdce67] // 4c8d0d0f870100 | dec eax // 8bda | mov ebx, edx // 4c8d05fe860100 | dec ebp condition: 7 of them and filesize < 801792 }
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