SYMBOLCOMMON_NAMEaka. SYNONYMS
win.rarstar (Back to overview)

rarstar

Actor(s): Tick


There is no description at this point.

References
2017-10-12SecureworksCTU Research Team
@online{team:20171012:bronze:7b9ae02, author = {CTU Research Team}, title = {{BRONZE BUTLER Targets Japanese Enterprises}}, date = {2017-10-12}, organization = {Secureworks}, url = {https://www.secureworks.com/research/bronze-butler-targets-japanese-businesses}, language = {English}, urldate = {2020-01-07} } BRONZE BUTLER Targets Japanese Enterprises
Daserf Datper rarstar xxmm Tick
Yara Rules
[TLP:WHITE] win_rarstar_auto (20201023 | autogenerated rule brought to you by yara-signator)
rule win_rarstar_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-12-22"
        version = "1"
        description = "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.rarstar"
        malpedia_rule_date = "20201222"
        malpedia_hash = "30354d830a29f0fbd3714d93d94dea941d77a130"
        malpedia_version = "20201023"
        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 = { 8d442434 8d4c2418 50 51 52 c684249010000001 c7442424ffffffff }
            // n = 7, score = 100
            //   8d442434             | lea                 eax, [esp + 0x34]
            //   8d4c2418             | lea                 ecx, [esp + 0x18]
            //   50                   | push                eax
            //   51                   | push                ecx
            //   52                   | push                edx
            //   c684249010000001     | mov                 byte ptr [esp + 0x1090], 1
            //   c7442424ffffffff     | mov                 dword ptr [esp + 0x24], 0xffffffff

        $sequence_1 = { 6a01 53 e8???????? 55 e8???????? 53 }
            // n = 6, score = 100
            //   6a01                 | push                1
            //   53                   | push                ebx
            //   e8????????           |                     
            //   55                   | push                ebp
            //   e8????????           |                     
            //   53                   | push                ebx

        $sequence_2 = { 83ec34 53 56 57 8365d800 c745dc94254000 8b4518 }
            // n = 7, score = 100
            //   83ec34               | sub                 esp, 0x34
            //   53                   | push                ebx
            //   56                   | push                esi
            //   57                   | push                edi
            //   8365d800             | and                 dword ptr [ebp - 0x28], 0
            //   c745dc94254000       | mov                 dword ptr [ebp - 0x24], 0x402594
            //   8b4518               | mov                 eax, dword ptr [ebp + 0x18]

        $sequence_3 = { 8944241c 51 be01000000 895c2418 }
            // n = 4, score = 100
            //   8944241c             | mov                 dword ptr [esp + 0x1c], eax
            //   51                   | push                ecx
            //   be01000000           | mov                 esi, 1
            //   895c2418             | mov                 dword ptr [esp + 0x18], ebx

        $sequence_4 = { 8bc6 8bca 85c9 7605 2bc1 83c003 8d14c500000000 }
            // n = 7, score = 100
            //   8bc6                 | mov                 eax, esi
            //   8bca                 | mov                 ecx, edx
            //   85c9                 | test                ecx, ecx
            //   7605                 | jbe                 7
            //   2bc1                 | sub                 eax, ecx
            //   83c003               | add                 eax, 3
            //   8d14c500000000       | lea                 edx, [eax*8]

        $sequence_5 = { ebe3 80a0a0d7400000 40 41 41 3bc6 72bf }
            // n = 7, score = 100
            //   ebe3                 | jmp                 0xffffffe5
            //   80a0a0d7400000       | and                 byte ptr [eax + 0x40d7a0], 0
            //   40                   | inc                 eax
            //   41                   | inc                 ecx
            //   41                   | inc                 ecx
            //   3bc6                 | cmp                 eax, esi
            //   72bf                 | jb                  0xffffffc1

        $sequence_6 = { 895c243c 894c2440 ff15???????? 85c0 7511 ff15???????? }
            // n = 6, score = 100
            //   895c243c             | mov                 dword ptr [esp + 0x3c], ebx
            //   894c2440             | mov                 dword ptr [esp + 0x40], ecx
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7511                 | jne                 0x13
            //   ff15????????         |                     

        $sequence_7 = { 0f8485000000 8b442410 8bfd 8d4801 33c0 8bd1 c1e902 }
            // n = 7, score = 100
            //   0f8485000000         | je                  0x8b
            //   8b442410             | mov                 eax, dword ptr [esp + 0x10]
            //   8bfd                 | mov                 edi, ebp
            //   8d4801               | lea                 ecx, [eax + 1]
            //   33c0                 | xor                 eax, eax
            //   8bd1                 | mov                 edx, ecx
            //   c1e902               | shr                 ecx, 2

        $sequence_8 = { 50 c705????????01000000 e8???????? 8b742424 }
            // n = 4, score = 100
            //   50                   | push                eax
            //   c705????????01000000     |     
            //   e8????????           |                     
            //   8b742424             | mov                 esi, dword ptr [esp + 0x24]

        $sequence_9 = { 85c0 7409 33c0 81c404080000 c3 }
            // n = 5, score = 100
            //   85c0                 | test                eax, eax
            //   7409                 | je                  0xb
            //   33c0                 | xor                 eax, eax
            //   81c404080000         | add                 esp, 0x804
            //   c3                   | ret                 

    condition:
        7 of them and filesize < 122880
}
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