SYMBOLCOMMON_NAMEaka. SYNONYMS
win.fancyfilter (Back to overview)

fancyfilter

aka: 0xFancyFilter

Actor(s): Equation Group


FancyFilter is a piece of code that documents code overlap between frameworks used by Regin and Equation Group.

References
2021-02-05EpicTurlaJuan Andrés Guerrero-Saade
@online{guerrerosaade:20210205:voltron:953cec2, author = {Juan Andrés Guerrero-Saade}, title = {{Voltron STA The curious case of 0xFancyFilter}}, date = {2021-02-05}, organization = {EpicTurla}, url = {https://www.epicturla.com/previous-works/hitb2020-voltron-sta}, language = {English}, urldate = {2021-02-06} } Voltron STA The curious case of 0xFancyFilter
fancyfilter MISTYVEAL Regin
Yara Rules
[TLP:WHITE] win_fancyfilter_auto (20220516 | Detects win.fancyfilter.)
rule win_fancyfilter_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.fancyfilter."
        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.fancyfilter"
        malpedia_rule_date = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 8b7832 03f9 8b4836 13ca }
            // n = 4, score = 400
            //   8b7832               | mov                 edi, dword ptr [eax + 0x32]
            //   03f9                 | add                 edi, ecx
            //   8b4836               | mov                 ecx, dword ptr [eax + 0x36]
            //   13ca                 | adc                 ecx, edx

        $sequence_1 = { 8b07 83e810 50 83c610 56 }
            // n = 5, score = 400
            //   8b07                 | mov                 eax, dword ptr [edi]
            //   83e810               | sub                 eax, 0x10
            //   50                   | push                eax
            //   83c610               | add                 esi, 0x10
            //   56                   | push                esi

        $sequence_2 = { 85c0 750d 8b472c a801 7406 83c804 }
            // n = 6, score = 400
            //   85c0                 | test                eax, eax
            //   750d                 | jne                 0xf
            //   8b472c               | mov                 eax, dword ptr [edi + 0x2c]
            //   a801                 | test                al, 1
            //   7406                 | je                  8
            //   83c804               | or                  eax, 4

        $sequence_3 = { 8b472c a801 7406 83c804 }
            // n = 4, score = 400
            //   8b472c               | mov                 eax, dword ptr [edi + 0x2c]
            //   a801                 | test                al, 1
            //   7406                 | je                  8
            //   83c804               | or                  eax, 4

        $sequence_4 = { 66833800 7404 b001 eb02 }
            // n = 4, score = 400
            //   66833800             | cmp                 word ptr [eax], 0
            //   7404                 | je                  6
            //   b001                 | mov                 al, 1
            //   eb02                 | jmp                 4

        $sequence_5 = { 81e3ffffff00 ff15???????? 50 ff15???????? 85c0 }
            // n = 5, score = 400
            //   81e3ffffff00         | and                 ebx, 0xffffff
            //   ff15????????         |                     
            //   50                   | push                eax
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax

        $sequence_6 = { b805400080 c20400 56 8b742408 8b4618 }
            // n = 5, score = 400
            //   b805400080           | mov                 eax, 0x80004005
            //   c20400               | ret                 4
            //   56                   | push                esi
            //   8b742408             | mov                 esi, dword ptr [esp + 8]
            //   8b4618               | mov                 eax, dword ptr [esi + 0x18]

        $sequence_7 = { 750d 8b472c a801 7406 }
            // n = 4, score = 400
            //   750d                 | jne                 0xf
            //   8b472c               | mov                 eax, dword ptr [edi + 0x2c]
            //   a801                 | test                al, 1
            //   7406                 | je                  8

        $sequence_8 = { 740f 8d4f20 51 50 ff15???????? }
            // n = 5, score = 400
            //   740f                 | je                  0x11
            //   8d4f20               | lea                 ecx, [edi + 0x20]
            //   51                   | push                ecx
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_9 = { a801 7406 83c804 89472c }
            // n = 4, score = 400
            //   a801                 | test                al, 1
            //   7406                 | je                  8
            //   83c804               | or                  eax, 4
            //   89472c               | mov                 dword ptr [edi + 0x2c], eax

    condition:
        7 of them and filesize < 169984
}
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