SYMBOLCOMMON_NAMEaka. SYNONYMS
win.grease (Back to overview)

GREASE


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References
2018-12-05NetScoutASERT Team
@online{team:20181205:stolen:bc9dd60, author = {ASERT Team}, title = {{STOLEN PENCIL Campaign Targets Academia}}, date = {2018-12-05}, organization = {NetScout}, url = {https://asert.arbornetworks.com/stolen-pencil-campaign-targets-academia/}, language = {English}, urldate = {2020-01-08} } STOLEN PENCIL Campaign Targets Academia
GREASE MECHANICAL
Yara Rules
[TLP:WHITE] win_grease_auto (20221125 | Detects win.grease.)
rule win_grease_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-11-21"
        version = "1"
        description = "Detects win.grease."
        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.grease"
        malpedia_rule_date = "20221118"
        malpedia_hash = "e0702e2e6d1d00da65c8a29a4ebacd0a4c59e1af"
        malpedia_version = "20221125"
        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 = { 52 50 683f000f00 50 50 50 }
            // n = 6, score = 400
            //   52                   | push                edx
            //   50                   | push                eax
            //   683f000f00           | push                0xf003f
            //   50                   | push                eax
            //   50                   | push                eax
            //   50                   | push                eax

        $sequence_1 = { 48897c2440 4889442438 48897c2430 4533c0 }
            // n = 4, score = 300
            //   48897c2440           | jne                 0xfb
            //   4889442438           | dec                 eax
            //   48897c2430           | mov                 ecx, dword ptr [esp + 0x60]
            //   4533c0               | test                eax, eax

        $sequence_2 = { 488b4c2460 48897c2440 488d442450 4889442438 48897c2430 }
            // n = 5, score = 300
            //   488b4c2460           | mov                 edx, ebx
            //   48897c2440           | mov                 dword ptr [esp + 0x28], 4
            //   488d442450           | dec                 eax
            //   4889442438           | mov                 dword ptr [esp + 0x20], eax
            //   48897c2430           | dec                 eax

        $sequence_3 = { ff15???????? b801000000 488b8c2480020000 4833cc e8???????? 4881c490020000 }
            // n = 6, score = 300
            //   ff15????????         |                     
            //   b801000000           | mov                 ecx, 0x80000002
            //   488b8c2480020000     | mov                 dword ptr [esp + 0x28], 0x2001f
            //   4833cc               | mov                 dword ptr [esp + 0x20], ebx
            //   e8????????           |                     
            //   4881c490020000       | test                eax, eax

        $sequence_4 = { 488b05???????? 4833c4 4889842480020000 488d4c2472 }
            // n = 4, score = 300
            //   488b05????????       |                     
            //   4833c4               | xor                 eax, eax
            //   4889842480020000     | dec                 eax
            //   488d4c2472           | mov                 edx, ebx

        $sequence_5 = { 488d442458 41b904000000 4533c0 488bd3 c744242804000000 4889442420 ff15???????? }
            // n = 7, score = 300
            //   488d442458           | dec                 eax
            //   41b904000000         | lea                 eax, [esp + 0x58]
            //   4533c0               | inc                 ecx
            //   488bd3               | mov                 ecx, 4
            //   c744242804000000     | inc                 ebp
            //   4889442420           | xor                 eax, eax
            //   ff15????????         |                     

        $sequence_6 = { 4533c0 48c7c102000080 c74424281f000200 895c2420 ff15???????? 85c0 0f85e7000000 }
            // n = 7, score = 300
            //   4533c0               | dec                 eax
            //   48c7c102000080       | mov                 edx, ebx
            //   c74424281f000200     | mov                 dword ptr [esp + 0x28], 4
            //   895c2420             | dec                 eax
            //   ff15????????         |                     
            //   85c0                 | mov                 dword ptr [esp + 0x20], eax
            //   0f85e7000000         | inc                 ebp

        $sequence_7 = { 85c0 7534 488b4c2450 488d442458 }
            // n = 4, score = 300
            //   85c0                 | mov                 ecx, dword ptr [esp + 0x60]
            //   7534                 | dec                 eax
            //   488b4c2450           | lea                 eax, [esp + 0x58]
            //   488d442458           | dec                 eax

        $sequence_8 = { 4533c0 c74424283f000f00 897c2420 ff15???????? }
            // n = 4, score = 300
            //   4533c0               | mov                 ecx, dword ptr [esp + 0x50]
            //   c74424283f000f00     | dec                 eax
            //   897c2420             | lea                 eax, [esp + 0x58]
            //   ff15????????         |                     

        $sequence_9 = { e9???????? c68434300900003a e9???????? c684343009000023 e9???????? c684343009000021 e9???????? }
            // n = 7, score = 200
            //   e9????????           |                     
            //   c68434300900003a     | mov                 byte ptr [esp + esi + 0x930], 0x3a
            //   e9????????           |                     
            //   c684343009000023     | mov                 byte ptr [esp + esi + 0x930], 0x23
            //   e9????????           |                     
            //   c684343009000021     | mov                 byte ptr [esp + esi + 0x930], 0x21
            //   e9????????           |                     

        $sequence_10 = { 8b44240c 8b35???????? 50 ffd6 8d4c2418 68???????? }
            // n = 6, score = 200
            //   8b44240c             | dec                 eax
            //   8b35????????         |                     
            //   50                   | mov                 dword ptr [esp + 0x40], edi
            //   ffd6                 | dec                 eax
            //   8d4c2418             | lea                 eax, [esp + 0x50]
            //   68????????           |                     

        $sequence_11 = { 3bf7 0f822dfdffff 8d84242c080000 50 55 ff15???????? 85c0 }
            // n = 7, score = 200
            //   3bf7                 | cmp                 esi, edi
            //   0f822dfdffff         | jb                  0xfffffd33
            //   8d84242c080000       | lea                 eax, [esp + 0x82c]
            //   50                   | push                eax
            //   55                   | push                ebp
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax

        $sequence_12 = { e9???????? c684341c04000077 e9???????? c684341c04000076 e9???????? c684341c04000065 e9???????? }
            // n = 7, score = 200
            //   e9????????           |                     
            //   c684341c04000077     | mov                 byte ptr [esp + esi + 0x41c], 0x77
            //   e9????????           |                     
            //   c684341c04000076     | mov                 byte ptr [esp + esi + 0x41c], 0x76
            //   e9????????           |                     
            //   c684341c04000065     | mov                 byte ptr [esp + esi + 0x41c], 0x65
            //   e9????????           |                     

        $sequence_13 = { 668984242c010000 6689842432010000 6689842438010000 b904000000 }
            // n = 4, score = 200
            //   668984242c010000     | dec                 eax
            //   6689842432010000     | mov                 dword ptr [esp + 0x38], eax
            //   6689842438010000     | dec                 eax
            //   b904000000           | mov                 dword ptr [esp + 0x30], edi

        $sequence_14 = { eb58 c68434200500003c eb4e c684342005000028 }
            // n = 4, score = 200
            //   eb58                 | jmp                 0x5a
            //   c68434200500003c     | mov                 byte ptr [esp + esi + 0x520], 0x3c
            //   eb4e                 | jmp                 0x50
            //   c684342005000028     | mov                 byte ptr [esp + esi + 0x520], 0x28

        $sequence_15 = { c68434200500005b eb6c c684342005000040 eb62 c68434200500007b eb58 c68434200500003c }
            // n = 7, score = 200
            //   c68434200500005b     | mov                 byte ptr [esp + esi + 0x520], 0x5b
            //   eb6c                 | jmp                 0x6e
            //   c684342005000040     | mov                 byte ptr [esp + esi + 0x520], 0x40
            //   eb62                 | jmp                 0x64
            //   c68434200500007b     | mov                 byte ptr [esp + esi + 0x520], 0x7b
            //   eb58                 | jmp                 0x5a
            //   c68434200500003c     | mov                 byte ptr [esp + esi + 0x520], 0x3c

        $sequence_16 = { 51 6a04 53 68???????? 52 c744242c05000000 }
            // n = 6, score = 200
            //   51                   | xor                 ecx, esp
            //   6a04                 | dec                 eax
            //   53                   | add                 esp, 0x290
            //   68????????           |                     
            //   52                   | dec                 eax
            //   c744242c05000000     | mov                 ecx, dword ptr [esp + 0x60]

        $sequence_17 = { 56 ff15???????? 33ed bb01000000 8d4c2420 68???????? }
            // n = 6, score = 200
            //   56                   | push                esi
            //   ff15????????         |                     
            //   33ed                 | xor                 ebp, ebp
            //   bb01000000           | mov                 ebx, 1
            //   8d4c2420             | lea                 ecx, [esp + 0x20]
            //   68????????           |                     

        $sequence_18 = { 75f7 2bc2 8bd0 8d442424 8d6801 }
            // n = 5, score = 200
            //   75f7                 | xor                 eax, esp
            //   2bc2                 | dec                 eax
            //   8bd0                 | mov                 dword ptr [esp + 0x280], eax
            //   8d442424             | dec                 eax
            //   8d6801               | lea                 ecx, [esp + 0x72]

        $sequence_19 = { 7408 80843418030000e0 46 3bf7 0f822dfdffff 8d842418030000 50 }
            // n = 7, score = 200
            //   7408                 | je                  0xa
            //   80843418030000e0     | add                 byte ptr [esp + esi + 0x318], 0xe0
            //   46                   | inc                 esi
            //   3bf7                 | cmp                 esi, edi
            //   0f822dfdffff         | jb                  0xfffffd33
            //   8d842418030000       | lea                 eax, [esp + 0x318]
            //   50                   | push                eax

        $sequence_20 = { 8d44242c 83c408 8d6801 8a08 }
            // n = 4, score = 200
            //   8d44242c             | mov                 eax, 1
            //   83c408               | dec                 eax
            //   8d6801               | mov                 ecx, dword ptr [esp + 0x280]
            //   8a08                 | dec                 eax

        $sequence_21 = { e8???????? 83c40c 53 8d942438050000 52 ffd6 }
            // n = 6, score = 200
            //   e8????????           |                     
            //   83c40c               | inc                 ebp
            //   53                   | xor                 eax, eax
            //   8d942438050000       | mov                 dword ptr [esp + 0x28], 0xf003f
            //   52                   | mov                 dword ptr [esp + 0x20], edi
            //   ffd6                 | dec                 eax

        $sequence_22 = { 53 6a25 8d942438030000 52 53 ff15???????? }
            // n = 6, score = 200
            //   53                   | dec                 eax
            //   6a25                 | mov                 ecx, dword ptr [esp + 0x60]
            //   8d942438030000       | mov                 eax, 1
            //   52                   | dec                 eax
            //   53                   | mov                 ecx, dword ptr [esp + 0x280]
            //   ff15????????         |                     

    condition:
        7 of them and filesize < 278528
}
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