SYMBOLCOMMON_NAMEaka. SYNONYMS
win.scout (Back to overview)

Scout

Actor(s): Lazarus Group

VTCollection    

A downloader that uses Windows messages to control its execution flow.

References
2023-10-13AhnLabASEC Analysis Team
Analysis Report on Lazarus Threat Group’s Volgmer and Scout Malware
JessieConTea Scout Volgmer
Yara Rules
[TLP:WHITE] win_scout_auto (20260504 | Detects win.scout.)
rule win_scout_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-05-04"
        version = "1"
        description = "Detects win.scout."
        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.scout"
        malpedia_rule_date = "20260422"
        malpedia_hash = "a182e35da64e6d71cb55f125c4d4225196523f14"
        malpedia_version = "20260504"
        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 = { 817c243031313131 7445 690d????????60ea0000 ff15???????? 8b0d???????? b867666666 ffc1 }
            // n = 7, score = 100
            //   817c243031313131     | dec                 eax
            //   7445                 | mov                 ebx, dword ptr [esp + 0x50]
            //   690d????????60ea0000     |     
            //   ff15????????         |                     
            //   8b0d????????         |                     
            //   b867666666           | dec                 eax
            //   ffc1                 | mov                 ebp, dword ptr [esp + 0x58]

        $sequence_1 = { 8d58b0 498bce 448bc3 488d154cac0000 e8???????? 85c0 }
            // n = 6, score = 100
            //   8d58b0               | inc                 ebp
            //   498bce               | xor                 ecx, ecx
            //   448bc3               | inc                 ebp
            //   488d154cac0000       | xor                 eax, eax
            //   e8????????           |                     
            //   85c0                 | dec                 eax

        $sequence_2 = { 7706 ff15???????? 488364243000 488d0d849f0000 8364242800 41b803000000 4533c9 }
            // n = 7, score = 100
            //   7706                 | mov                 ecx, 0x80000002
            //   ff15????????         |                     
            //   488364243000         | test                eax, eax
            //   488d0d849f0000       | je                  0xf9
            //   8364242800           | dec                 eax
            //   41b803000000         | mov                 ecx, ebx
            //   4533c9               | xor                 eax, eax

        $sequence_3 = { 83c8ff eb0b 4803f6 418b84f728950100 }
            // n = 4, score = 100
            //   83c8ff               | je                  0x93
            //   eb0b                 | dec                 eax
            //   4803f6               | lea                 edi, [0x190d4]
            //   418b84f728950100     | jmp                 0xa4

        $sequence_4 = { 0f84aa000000 83f81a 0f85eb020000 33ff 488d4c2430 48897c2430 }
            // n = 6, score = 100
            //   0f84aa000000         | dec                 eax
            //   83f81a               | lea                 esi, [ebx + 0x128]
            //   0f85eb020000         | mov                 ebp, 6
            //   33ff                 | dec                 eax
            //   488d4c2430           | lea                 edi, [ebx + 0x38]
            //   48897c2430           | dec                 eax

        $sequence_5 = { 488b8d80140000 ff15???????? 488d537c 41b888140000 }
            // n = 4, score = 100
            //   488b8d80140000       | mov                 eax, dword ptr [ebx]
            //   ff15????????         |                     
            //   488d537c             | jmp                 0x441
            //   41b888140000         | dec                 eax

        $sequence_6 = { 4885c9 750b 488d0d29f10000 48894b48 4963d0 e8???????? }
            // n = 6, score = 100
            //   4885c9               | mov                 eax, edx
            //   750b                 | jae                 0xc6d
            //   488d0d29f10000       | dec                 eax
            //   48894b48             | mov                 ecx, edx
            //   4963d0               | dec                 esp
            //   e8????????           |                     

        $sequence_7 = { 488d0d36fbfeff 83e03f 458be9 4d03e8 4c8945df 4c8be6 }
            // n = 6, score = 100
            //   488d0d36fbfeff       | lea                 ebx, [ebx + 2]
            //   83e03f               | dec                 eax
            //   458be9               | mov                 eax, 0xffffffff
            //   4d03e8               | dec                 eax
            //   4c8945df             | lea                 ecx, [ebp - 0x10]
            //   4c8be6               | movzx               eax, word ptr [ebp + ebx*2 - 0x10]

        $sequence_8 = { 488d0dd4f90000 4183e23f 4d03f0 4d8bf8 }
            // n = 4, score = 100
            //   488d0dd4f90000       | je                  0x748
            //   4183e23f             | dec                 eax
            //   4d03f0               | mov                 dword ptr [esp + 0x20], eax
            //   4d8bf8               | dec                 eax

        $sequence_9 = { 0f84aa000000 83f81a 0f85eb020000 33ff 488d4c2430 48897c2430 e8???????? }
            // n = 7, score = 100
            //   0f84aa000000         | lea                 ecx, [0xbf79]
            //   83f81a               | xor                 ecx, ecx
            //   0f85eb020000         | dec                 esp
            //   33ff                 | lea                 eax, [0xbf6c]
            //   488d4c2430           | dec                 eax
            //   48897c2430           | lea                 edx, [0xbf6d]
            //   e8????????           |                     

    condition:
        7 of them and filesize < 315392
}
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