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 = "2023-03-28" 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 = "20230328" malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d" malpedia_version = "20230407" 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 = { 894704 33c9 b800000040 0fa2 } // n = 4, score = 900 // 894704 | mov dword ptr [edi + 4], eax // 33c9 | xor ecx, ecx // b800000040 | mov eax, 0x40000000 // 0fa2 | cpuid $sequence_2 = { f7411400000020 7407 8b41f8 3901 } // n = 4, 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 $sequence_3 = { 0fa2 89442420 895c2424 894c2428 8954242c 0f31 } // n = 6, score = 900 // 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 // 0f31 | rdtsc $sequence_4 = { ff15???????? 25ffffff00 0d00000005 e9???????? 8bd7 } // n = 5, score = 900 // ff15???????? | // 25ffffff00 | and eax, 0xffffff // 0d00000005 | or eax, 0x5000000 // e9???????? | // 8bd7 | mov edx, edi $sequence_5 = { 33ff 8bf7 8d6f10 ff15???????? 0f31 } // n = 5, score = 900 // 33ff | xor edi, edi // 8bf7 | mov esi, edi // 8d6f10 | lea ebp, [edi + 0x10] // ff15???????? | // 0f31 | rdtsc $sequence_6 = { 33c9 b801000000 0fa2 89442420 } // n = 4, score = 900 // 33c9 | xor ecx, ecx // b801000000 | mov eax, 1 // 0fa2 | cpuid // 89442420 | mov dword ptr [esp + 0x20], eax $sequence_7 = { ffd0 ff15???????? 25ffffff00 0fbae81b } // n = 4, score = 900 // ffd0 | call eax // ff15???????? | // 25ffffff00 | and eax, 0xffffff // 0fbae81b | bts eax, 0x1b $sequence_8 = { 6685c0 741a 57 8bfb 8bc8 } // n = 5, score = 200 // 6685c0 | test ax, ax // 741a | je 0x1c // 57 | push edi // 8bfb | mov edi, ebx // 8bc8 | mov ecx, eax $sequence_9 = { ff742410 8b35???????? 68???????? 68???????? 53 ffd6 } // n = 6, score = 200 // ff742410 | push dword ptr [esp + 0x10] // 8b35???????? | // 68???????? | // 68???????? | // 53 | push ebx // ffd6 | call esi $sequence_10 = { 50 ff15???????? 8d442418 50 8d542418 8d4c2434 } // n = 6, score = 200 // 50 | push eax // ff15???????? | // 8d442418 | lea eax, [esp + 0x18] // 50 | push eax // 8d542418 | lea edx, [esp + 0x18] // 8d4c2434 | lea ecx, [esp + 0x34] $sequence_11 = { e8???????? 50 55 8d047b 68???????? } // n = 5, score = 200 // e8???????? | // 50 | push eax // 55 | push ebp // 8d047b | lea eax, [ebx + edi*2] // 68???????? | $sequence_12 = { 51 8d4dfc ba???????? 51 } // n = 4, score = 200 // 51 | push ecx // 8d4dfc | lea ecx, [ebp - 4] // ba???????? | // 51 | push ecx $sequence_13 = { 81c444010000 c3 83ec10 53 55 } // n = 5, score = 200 // 81c444010000 | add esp, 0x144 // c3 | ret // 83ec10 | sub esp, 0x10 // 53 | push ebx // 55 | push ebp $sequence_14 = { 8b8690010000 85c0 7426 83f808 7721 50 8d8694010000 } // n = 7, score = 200 // 8b8690010000 | mov eax, dword ptr [esi + 0x190] // 85c0 | test eax, eax // 7426 | je 0x28 // 83f808 | cmp eax, 8 // 7721 | ja 0x23 // 50 | push eax // 8d8694010000 | lea eax, [esi + 0x194] condition: 7 of them and filesize < 98304 }
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