SYMBOLCOMMON_NAMEaka. SYNONYMS
win.unidentified_078 (Back to overview)

Unidentified 078 (Zebrocy Nim Loader?)

Actor(s): APT28

VTCollection    

Suspected Zebrocy loader written in Nim.

References
2020-09-01 ⋅ Twitter (@Vishnyak0v) ⋅ Alexey Vishnyakov
Tweet on sample discovery
Unidentified 078 (Zebrocy Nim Loader?)
Yara Rules
[TLP:WHITE] win_unidentified_078_auto (20260917 | Detects win.unidentified_078.)
rule win_unidentified_078_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        version = "1"
        description = "Detects win.unidentified_078."
        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.unidentified_078"
        malpedia_rule_date = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 0f8412010000 0f8cee000000 80fa0d 0f8421010000 80fa1b 0f8576010000 }
            // n = 6, score = 200
            //   0f8412010000         | dec                 eax
            //   0f8cee000000         | mov                 dword ptr [esp + 0x30], eax
            //   80fa0d               | jmp                 0xe65
            //   0f8421010000         | mov                 edx, 2
            //   80fa1b               | dec                 eax
            //   0f8576010000         | mov                 ecx, ebx

        $sequence_1 = { 0f849a000000 f6420901 0f8590000000 8a4a08 80f91c 0f8784000000 b801000000 }
            // n = 7, score = 200
            //   0f849a000000         | dec                 esp
            //   f6420901             | mov                 ebp, dword ptr [ebp]
            //   0f8590000000         | dec                 esp
            //   8a4a08               | lea                 esi, [0xc716]
            //   80f91c               | xor                 edi, edi
            //   0f8784000000         | dec                 esp
            //   b801000000           | lea                 esp, [0xc6dd]

        $sequence_2 = { 8a441310 3c5c 7404 3c2f }
            // n = 4, score = 200
            //   8a441310             | inc                 esp
            //   3c5c                 | add                 eax, dword ptr [ecx + 8]
            //   7404                 | mov                 eax, edx
            //   3c2f                 | je                  0x2b

        $sequence_3 = { 83eb5b 83fb01 0f8720010000 eb0f b901003b00 }
            // n = 5, score = 200
            //   83eb5b               | cmp                 dword ptr [edi + 8], 0x3f000000
            //   83fb01               | jle                 0x52f
            //   0f8720010000         | dec                 eax
            //   eb0f                 | mov                 edx, edi
            //   b901003b00           | dec                 eax

        $sequence_4 = { 3c18 0f8483000000 3c1c 740d 3c16 }
            // n = 5, score = 200
            //   3c18                 | mov                 ebx, dword ptr [esi + 8]
            //   0f8483000000         | dec                 eax
            //   3c1c                 | mov                 ecx, dword ptr [esp + 0x38]
            //   740d                 | je                  0x224
            //   3c16                 | dec                 eax

        $sequence_5 = { b901010000 ff15???????? 85c0 740e }
            // n = 4, score = 200
            //   b901010000           | dec                 eax
            //   ff15????????         |                     
            //   85c0                 | mov                 ecx, dword ptr [edi + ebx]
            //   740e                 | lea                 ebp, [0x22528]

        $sequence_6 = { 80fa28 0f8d94010000 80fa26 0f8f18010000 80fa23 }
            // n = 5, score = 200
            //   80fa28               | dec                 esp
            //   0f8d94010000         | mov                 ecx, edi
            //   80fa26               | cmp                 word ptr [ebp + 2], 0
            //   0f8f18010000         | dec                 esp
            //   80fa23               | lea                 edi, [ebp + 2]

        $sequence_7 = { 83fb11 743f 81fba2000000 7437 89da 83e2fd }
            // n = 6, score = 200
            //   83fb11               | dec                 edi
            //   743f                 | lea                 edx, [eax + ecx - 0x38]
            //   81fba2000000         | dec                 ebp
            //   7437                 | mov                 ebx, dword ptr [edx]
            //   89da                 | dec                 ecx
            //   83e2fd               | ja                  0x31a

        $sequence_8 = { e9???????? 80fa0c 0f8412010000 0f8cee000000 80fa0d }
            // n = 5, score = 200
            //   e9????????           |                     
            //   80fa0c               | dec                 eax
            //   0f8412010000         | mov                 eax, dword ptr [esi + 0x3458]
            //   0f8cee000000         | dec                 eax
            //   80fa0d               | mov                 edx, dword ptr [eax]

        $sequence_9 = { 7514 8a542e10 80fa5c 0f94c1 }
            // n = 4, score = 200
            //   7514                 | dec                 eax
            //   8a542e10             | mov                 eax, ebx
            //   80fa5c               | je                  0x272
            //   0f94c1               | dec                 eax

    condition:
        7 of them and filesize < 688128
}
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