A loader used to deliver IcedID, fetching a fake image from which payloads are extracted.
rule win_photoloader_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.photoloader." 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.photoloader" malpedia_rule_date = "20230124" malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686" malpedia_version = "20230125" 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 = { c0c003 0fb6c8 8bc1 83e10f } // n = 4, score = 1100 // c0c003 | rol al, 3 // 0fb6c8 | movzx ecx, al // 8bc1 | mov eax, ecx // 83e10f | and ecx, 0xf $sequence_1 = { ff15???????? 85c0 744c 0fb64301 } // n = 4, score = 900 // ff15???????? | // 85c0 | test eax, eax // 744c | je 0x4e // 0fb64301 | movzx eax, byte ptr [ebx + 1] $sequence_2 = { 0fa2 894704 33c9 b800000040 0fa2 895f0c e8???????? } // n = 7, score = 900 // 0fa2 | cpuid // 894704 | mov dword ptr [edi + 4], eax // 33c9 | xor ecx, ecx // b800000040 | mov eax, 0x40000000 // 0fa2 | cpuid // 895f0c | mov dword ptr [edi + 0xc], ebx // e8???????? | $sequence_3 = { 33c9 b801000000 0fa2 89442420 895c2424 894c2428 8954242c } // n = 7, score = 900 // 33c9 | xor ecx, ecx // b801000000 | mov eax, 1 // 0fa2 | cpuid // 89442420 | mov dword ptr [esp + 0x20], eax // 895c2424 | mov dword ptr [esp + 0x24], ebx // 894c2428 | mov dword ptr [esp + 0x28], ecx // 8954242c | mov dword ptr [esp + 0x2c], edx $sequence_4 = { 33ff 8bf7 8d6f10 ff15???????? } // n = 4, score = 900 // 33ff | xor edi, edi // 8bf7 | mov esi, edi // 8d6f10 | lea ebp, [edi + 0x10] // ff15???????? | $sequence_5 = { ff15???????? 85c0 0f85d2000000 ff15???????? 83f87a 0f85c3000000 8b457f } // n = 7, score = 900 // ff15???????? | // 85c0 | test eax, eax // 0f85d2000000 | jne 0xd8 // ff15???????? | // 83f87a | cmp eax, 0x7a // 0f85c3000000 | jne 0xc9 // 8b457f | mov eax, dword ptr [ebp + 0x7f] $sequence_6 = { f7411400000020 7407 8b41f8 3901 7714 } // n = 5, score = 900 // f7411400000020 | test dword ptr [ecx + 0x14], 0x20000000 // 7407 | je 9 // 8b41f8 | mov eax, dword ptr [ecx - 8] // 3901 | cmp dword ptr [ecx], eax // 7714 | ja 0x16 $sequence_7 = { 0f85c3000000 8b457f 85c0 0f84b8000000 8bd8 ff15???????? } // n = 6, score = 900 // 0f85c3000000 | jne 0xc9 // 8b457f | mov eax, dword ptr [ebp + 0x7f] // 85c0 | test eax, eax // 0f84b8000000 | je 0xbe // 8bd8 | mov ebx, eax // ff15???????? | $sequence_8 = { 50 55 8bda ff15???????? } // n = 4, score = 200 // 50 | pop ecx // 55 | cmp word ptr [esp + 0x14], cx // 8bda | push eax // ff15???????? | $sequence_9 = { 51 ffd0 33c0 6a09 59 66394c2414 } // n = 6, score = 200 // 51 | mov eax, ecx // ffd0 | and ecx, 0xf // 33c0 | push ecx // 6a09 | call eax // 59 | xor eax, eax // 66394c2414 | push 9 $sequence_10 = { 8d7c2414 03f0 6a09 58 } // n = 4, score = 200 // 8d7c2414 | test bl, bl // 03f0 | je 0x21 // 6a09 | lea edi, [esp + 0x14] // 58 | add esi, eax $sequence_11 = { 8bc3 8b7608 2bf7 fec3 0fb6db } // n = 5, score = 200 // 8bc3 | test eax, eax // 8b7608 | je 0xd0 // 2bf7 | mov eax, ebx // fec3 | mov esi, dword ptr [esi + 8] // 0fb6db | sub esi, edi $sequence_12 = { ffd6 03f8 83c420 8d0c7b e8???????? 03f8 8d0c7b } // n = 7, score = 200 // ffd6 | inc bl // 03f8 | movzx ebx, bl // 83c420 | call esi // 8d0c7b | add edi, eax // e8???????? | // 03f8 | add esp, 0x20 // 8d0c7b | lea ecx, [ebx + edi*2] $sequence_13 = { 68???????? ff15???????? 50 ff15???????? 8bf8 85ff 7445 } // n = 7, score = 200 // 68???????? | // ff15???????? | // 50 | add edi, eax // ff15???????? | // 8bf8 | lea ecx, [ebx + edi*2] // 85ff | push eax // 7445 | mov edi, eax $sequence_14 = { 7423 8b55f4 85d2 741c 84db 741f } // n = 6, score = 200 // 7423 | test edi, edi // 8b55f4 | je 0x47 // 85d2 | je 0x25 // 741c | mov edx, dword ptr [ebp - 0xc] // 84db | test edx, edx // 741f | je 0x1e condition: 7 of them and filesize < 98304 }
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