According to Recorded Future, IsaacWiper is a destructive malware that overwrites all physical disks and logical volumes on a victim’s machine.
rule win_isaacwiper_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" version = "1" description = "Detects win.isaacwiper." 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.isaacwiper" malpedia_rule_date = "20260916" malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6" malpedia_version = "20260917" 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 = { 81ec18010000 56 57 6a00 8d4c241c e8???????? 8b3d???????? } // n = 7, score = 100 // 81ec18010000 | sub esp, 0x118 // 56 | push esi // 57 | push edi // 6a00 | push 0 // 8d4c241c | lea ecx, [esp + 0x1c] // e8???????? | // 8b3d???????? | $sequence_1 = { ff5010 0fb7c0 89442410 8a03 3c7f 0f8492000000 84c0 } // n = 7, score = 100 // ff5010 | call dword ptr [eax + 0x10] // 0fb7c0 | movzx eax, ax // 89442410 | mov dword ptr [esp + 0x10], eax // 8a03 | mov al, byte ptr [ebx] // 3c7f | cmp al, 0x7f // 0f8492000000 | je 0x98 // 84c0 | test al, al $sequence_2 = { 331486 81e2ffffff7f 331486 8bca d1ea } // n = 5, score = 100 // 331486 | xor edx, dword ptr [esi + eax*4] // 81e2ffffff7f | and edx, 0x7fffffff // 331486 | xor edx, dword ptr [esi + eax*4] // 8bca | mov ecx, edx // d1ea | shr edx, 1 $sequence_3 = { e8???????? 8ad0 83c404 33c0 85db } // n = 5, score = 100 // e8???????? | // 8ad0 | mov dl, al // 83c404 | add esp, 4 // 33c0 | xor eax, eax // 85db | test ebx, ebx $sequence_4 = { e8???????? 8b4de0 8b01 8b4008 ffd0 85c0 740a } // n = 7, score = 100 // e8???????? | // 8b4de0 | mov ecx, dword ptr [ebp - 0x20] // 8b01 | mov eax, dword ptr [ecx] // 8b4008 | mov eax, dword ptr [eax + 8] // ffd0 | call eax // 85c0 | test eax, eax // 740a | je 0xc $sequence_5 = { 8bc8 e8???????? 8bce c744242000000000 } // n = 4, score = 100 // 8bc8 | mov ecx, eax // e8???????? | // 8bce | mov ecx, esi // c744242000000000 | mov dword ptr [esp + 0x20], 0 $sequence_6 = { c1e80b 47 33c8 897df8 8bc1 25ad583aff c1e007 } // n = 7, score = 100 // c1e80b | shr eax, 0xb // 47 | inc edi // 33c8 | xor ecx, eax // 897df8 | mov dword ptr [ebp - 8], edi // 8bc1 | mov eax, ecx // 25ad583aff | and eax, 0xff3a58ad // c1e007 | shl eax, 7 $sequence_7 = { 57 6bf838 8955fc 8b0495e8670310 } // n = 4, score = 100 // 57 | push edi // 6bf838 | imul edi, eax, 0x38 // 8955fc | mov dword ptr [ebp - 4], edx // 8b0495e8670310 | mov eax, dword ptr [edx*4 + 0x100367e8] $sequence_8 = { 0f84dd000000 50 8d458c 50 e8???????? } // n = 5, score = 100 // 0f84dd000000 | je 0xe3 // 50 | push eax // 8d458c | lea eax, [ebp - 0x74] // 50 | push eax // e8???????? | $sequence_9 = { 8d41e0 89443184 8b4698 8b4004 c7443098d8270310 8b4698 } // n = 6, score = 100 // 8d41e0 | lea eax, [ecx - 0x20] // 89443184 | mov dword ptr [ecx + esi - 0x7c], eax // 8b4698 | mov eax, dword ptr [esi - 0x68] // 8b4004 | mov eax, dword ptr [eax + 4] // c7443098d8270310 | mov dword ptr [eax + esi - 0x68], 0x100327d8 // 8b4698 | mov eax, dword ptr [esi - 0x68] condition: 7 of them and filesize < 467968 }
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