SYMBOLCOMMON_NAMEaka. SYNONYMS
win.fancyfilter (Back to overview)

fancyfilter

aka: 0xFancyFilter

Actor(s): Equation Group

VTCollection    

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
Voltron STA The curious case of 0xFancyFilter
fancyfilter MISTYVEAL Regin
Yara Rules
[TLP:WHITE] win_fancyfilter_auto (20230808 | Detects win.fancyfilter.)
rule win_fancyfilter_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-12-06"
        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 = "20231130"
        malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351"
        malpedia_version = "20230808"
        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 = { 740a 66833800 7404 b001 eb02 }
            // n = 5, score = 400
            //   740a                 | je                  0xc
            //   66833800             | cmp                 word ptr [eax], 0
            //   7404                 | je                  6
            //   b001                 | mov                 al, 1
            //   eb02                 | jmp                 4

        $sequence_1 = { a1???????? 83c012 50 ff15???????? }
            // n = 4, score = 400
            //   a1????????           |                     
            //   83c012               | add                 eax, 0x12
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_2 = { 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_3 = { ff15???????? 83c420 83f803 7409 83f806 }
            // n = 5, score = 400
            //   ff15????????         |                     
            //   83c420               | add                 esp, 0x20
            //   83f803               | cmp                 eax, 3
            //   7409                 | je                  0xb
            //   83f806               | cmp                 eax, 6

        $sequence_4 = { 83c012 50 ffd6 a1???????? }
            // n = 4, score = 400
            //   83c012               | add                 eax, 0x12
            //   50                   | push                eax
            //   ffd6                 | call                esi
            //   a1????????           |                     

        $sequence_5 = { 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_6 = { 85c0 740a 66833800 7404 b001 eb02 }
            // n = 6, score = 400
            //   85c0                 | test                eax, eax
            //   740a                 | je                  0xc
            //   66833800             | cmp                 word ptr [eax], 0
            //   7404                 | je                  6
            //   b001                 | mov                 al, 1
            //   eb02                 | jmp                 4

        $sequence_7 = { 81e3ffffff00 ff15???????? 50 ff15???????? }
            // n = 4, score = 400
            //   81e3ffffff00         | and                 ebx, 0xffffff
            //   ff15????????         |                     
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_8 = { 85c0 740a 66833800 7404 b001 }
            // n = 5, score = 400
            //   85c0                 | test                eax, eax
            //   740a                 | je                  0xc
            //   66833800             | cmp                 word ptr [eax], 0
            //   7404                 | je                  6
            //   b001                 | mov                 al, 1

        $sequence_9 = { b805400080 c20400 56 8b742408 }
            // n = 4, score = 400
            //   b805400080           | mov                 eax, 0x80004005
            //   c20400               | ret                 4
            //   56                   | push                esi
            //   8b742408             | mov                 esi, dword ptr [esp + 8]

    condition:
        7 of them and filesize < 169984
}
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