Actor(s): Handala
According to Intezer, this is a shellcode loader.
rule win_flash_develop_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2024-10-31" version = "1" description = "Detects win.flash_develop." 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.flash_develop" malpedia_rule_date = "20241030" malpedia_hash = "26e26953c49c8efafbf72a38076855d578e0a2e4" malpedia_version = "20241030" 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 = { 55 56 33c9 57 0fb68170034200 99 8bf0 } // n = 7, score = 100 // 55 | push ebp // 56 | push esi // 33c9 | xor ecx, ecx // 57 | push edi // 0fb68170034200 | movzx eax, byte ptr [ecx + 0x420370] // 99 | cdq // 8bf0 | mov esi, eax $sequence_1 = { 33fa 0fa4f708 c1e608 8934cd40484800 99 } // n = 5, score = 100 // 33fa | xor edi, edx // 0fa4f708 | shld edi, esi, 8 // c1e608 | shl esi, 8 // 8934cd40484800 | mov dword ptr [ecx*8 + 0x484840], esi // 99 | cdq $sequence_2 = { c78424c8020000e0b04600 c78424cc02000068df4600 c78424d0020000b40d4700 c78424d4020000503e4700 c78424d8020000446e4700 c78424dc0200000c9d4700 c78424e0020000b0cc4700 } // n = 7, score = 100 // c78424c8020000e0b04600 | mov dword ptr [esp + 0x2c8], 0x46b0e0 // c78424cc02000068df4600 | mov dword ptr [esp + 0x2cc], 0x46df68 // c78424d0020000b40d4700 | mov dword ptr [esp + 0x2d0], 0x470db4 // c78424d4020000503e4700 | mov dword ptr [esp + 0x2d4], 0x473e50 // c78424d8020000446e4700 | mov dword ptr [esp + 0x2d8], 0x476e44 // c78424dc0200000c9d4700 | mov dword ptr [esp + 0x2dc], 0x479d0c // c78424e0020000b0cc4700 | mov dword ptr [esp + 0x2e0], 0x47ccb0 $sequence_3 = { 891ccd28184800 892ccd2c184800 0fa4f710 c1e610 33f0 33fa 0fa4f708 } // n = 7, score = 100 // 891ccd28184800 | mov dword ptr [ecx*8 + 0x481828], ebx // 892ccd2c184800 | mov dword ptr [ecx*8 + 0x48182c], ebp // 0fa4f710 | shld edi, esi, 0x10 // c1e610 | shl esi, 0x10 // 33f0 | xor esi, eax // 33fa | xor edi, edx // 0fa4f708 | shld edi, esi, 8 $sequence_4 = { 33fa c1e308 892ccd2c204800 8bef 0fa4f708 891ccd28204800 8bde } // n = 7, score = 100 // 33fa | xor edi, edx // c1e308 | shl ebx, 8 // 892ccd2c204800 | mov dword ptr [ecx*8 + 0x48202c], ebp // 8bef | mov ebp, edi // 0fa4f708 | shld edi, esi, 8 // 891ccd28204800 | mov dword ptr [ecx*8 + 0x482028], ebx // 8bde | mov ebx, esi $sequence_5 = { 893ccd44484800 8bf0 8bfa 0fa4f708 } // n = 4, score = 100 // 893ccd44484800 | mov dword ptr [ecx*8 + 0x484844], edi // 8bf0 | mov esi, eax // 8bfa | mov edi, edx // 0fa4f708 | shld edi, esi, 8 $sequence_6 = { 892ccd34204800 8bef 0fa4f708 33fa 891ccd30204800 8bde c1e608 } // n = 7, score = 100 // 892ccd34204800 | mov dword ptr [ecx*8 + 0x482034], ebp // 8bef | mov ebp, edi // 0fa4f708 | shld edi, esi, 8 // 33fa | xor edi, edx // 891ccd30204800 | mov dword ptr [ecx*8 + 0x482030], ebx // 8bde | mov ebx, esi // c1e608 | shl esi, 8 $sequence_7 = { c7842464010000240a4200 c7842468010000043a4200 c784246c01000070694200 c7842470010000cc9a4200 } // n = 4, score = 100 // c7842464010000240a4200 | mov dword ptr [esp + 0x164], 0x420a24 // c7842468010000043a4200 | mov dword ptr [esp + 0x168], 0x423a04 // c784246c01000070694200 | mov dword ptr [esp + 0x16c], 0x426970 // c7842470010000cc9a4200 | mov dword ptr [esp + 0x170], 0x429acc $sequence_8 = { 0fb68170054200 33ea 0fa4dd10 33fa 99 8934cd28304800 } // n = 6, score = 100 // 0fb68170054200 | movzx eax, byte ptr [ecx + 0x420570] // 33ea | xor ebp, edx // 0fa4dd10 | shld ebp, ebx, 0x10 // 33fa | xor edi, edx // 99 | cdq // 8934cd28304800 | mov dword ptr [ecx*8 + 0x483028], esi $sequence_9 = { 893ccd44404800 83c104 81f900010000 0f8c39f8ffff 5f 5e 5d } // n = 7, score = 100 // 893ccd44404800 | mov dword ptr [ecx*8 + 0x484044], edi // 83c104 | add ecx, 4 // 81f900010000 | cmp ecx, 0x100 // 0f8c39f8ffff | jl 0xfffff83f // 5f | pop edi // 5e | pop esi // 5d | pop ebp condition: 7 of them and filesize < 1111040 }
If your designated proposal does not fit in any other category, feel free to write a free-text in the comment field below. Changes regarding references should be proposed on the Malpedia library page.
Your suggestion will be reviewed before being published. Thank you for contributing!
YYYY-MM-DD
YYYY-MM
YYYY