SYMBOLCOMMON_NAMEaka. SYNONYMS
win.ketrum (Back to overview)

Ketrum

Actor(s): Mirage


Intezer found this family mid May 2020, which appears to be a merger of the family Ketrican and Okrum.

References
2020-05-21IntezerPaul Litvak
@online{litvak:20200521:evolution:a14bf60, author = {Paul Litvak}, title = {{The Evolution of APT15’s Codebase 2020}}, date = {2020-05-21}, organization = {Intezer}, url = {https://www.intezer.com/blog/research/the-evolution-of-apt15s-codebase-2020/}, language = {English}, urldate = {2020-05-23} } The Evolution of APT15’s Codebase 2020
Ketrican Ketrum Okrum
Yara Rules
[TLP:WHITE] win_ketrum_auto (20201023 | autogenerated rule brought to you by yara-signator)
rule win_ketrum_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.ketrum"
        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 = { 6bf603 8985eccbffff 8d4604 50 }
            // n = 4, score = 200
            //   6bf603               | imul                esi, esi, 3
            //   8985eccbffff         | mov                 dword ptr [ebp - 0x3414], eax
            //   8d4604               | lea                 eax, [esi + 4]
            //   50                   | push                eax

        $sequence_1 = { 0fb6c0 8a8405f4feffff 32043a 8807 }
            // n = 4, score = 200
            //   0fb6c0               | movzx               eax, al
            //   8a8405f4feffff       | mov                 al, byte ptr [ebp + eax - 0x10c]
            //   32043a               | xor                 al, byte ptr [edx + edi]
            //   8807                 | mov                 byte ptr [edi], al

        $sequence_2 = { 8d85fcfbffff 50 8d8dfcf7ffff e8???????? 50 }
            // n = 5, score = 200
            //   8d85fcfbffff         | lea                 eax, [ebp - 0x404]
            //   50                   | push                eax
            //   8d8dfcf7ffff         | lea                 ecx, [ebp - 0x804]
            //   e8????????           |                     
            //   50                   | push                eax

        $sequence_3 = { b8???????? ffb5f0bfffff 68???????? ffb5f8bfffff }
            // n = 4, score = 200
            //   b8????????           |                     
            //   ffb5f0bfffff         | push                dword ptr [ebp - 0x4010]
            //   68????????           |                     
            //   ffb5f8bfffff         | push                dword ptr [ebp - 0x4008]

        $sequence_4 = { 53 ffb5dccbffff 50 68???????? 56 e8???????? ffb5eccbffff }
            // n = 7, score = 200
            //   53                   | push                ebx
            //   ffb5dccbffff         | push                dword ptr [ebp - 0x3424]
            //   50                   | push                eax
            //   68????????           |                     
            //   56                   | push                esi
            //   e8????????           |                     
            //   ffb5eccbffff         | push                dword ptr [ebp - 0x3414]

        $sequence_5 = { 0500040000 50 e8???????? 8b15???????? }
            // n = 4, score = 200
            //   0500040000           | add                 eax, 0x400
            //   50                   | push                eax
            //   e8????????           |                     
            //   8b15????????         |                     

        $sequence_6 = { 8985f8cbffff 6a03 59 33d2 }
            // n = 4, score = 200
            //   8985f8cbffff         | mov                 dword ptr [ebp - 0x3408], eax
            //   6a03                 | push                3
            //   59                   | pop                 ecx
            //   33d2                 | xor                 edx, edx

        $sequence_7 = { 68???????? ffb5f4cbffff 68???????? ffb5f8cbffff ffb5e8cbffff ffb5e4cbffff }
            // n = 6, score = 200
            //   68????????           |                     
            //   ffb5f4cbffff         | push                dword ptr [ebp - 0x340c]
            //   68????????           |                     
            //   ffb5f8cbffff         | push                dword ptr [ebp - 0x3408]
            //   ffb5e8cbffff         | push                dword ptr [ebp - 0x3418]
            //   ffb5e4cbffff         | push                dword ptr [ebp - 0x341c]

        $sequence_8 = { 40 3bc6 7ce8 c6800815420000 56 e8???????? 807d0800 }
            // n = 7, score = 100
            //   40                   | inc                 eax
            //   3bc6                 | cmp                 eax, esi
            //   7ce8                 | jl                  0xffffffea
            //   c6800815420000       | mov                 byte ptr [eax + 0x421508], 0
            //   56                   | push                esi
            //   e8????????           |                     
            //   807d0800             | cmp                 byte ptr [ebp + 8], 0

        $sequence_9 = { 68f4010000 ff15???????? 834dfcff 6a01 33ff 8db5ccfeffff }
            // n = 6, score = 100
            //   68f4010000           | push                0x1f4
            //   ff15????????         |                     
            //   834dfcff             | or                  dword ptr [ebp - 4], 0xffffffff
            //   6a01                 | push                1
            //   33ff                 | xor                 edi, edi
            //   8db5ccfeffff         | lea                 esi, [ebp - 0x134]

        $sequence_10 = { d1fe 8d0c71 8908 8b450c 3945f4 0f843efbffff }
            // n = 6, score = 100
            //   d1fe                 | sar                 esi, 1
            //   8d0c71               | lea                 ecx, [ecx + esi*2]
            //   8908                 | mov                 dword ptr [eax], ecx
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   3945f4               | cmp                 dword ptr [ebp - 0xc], eax
            //   0f843efbffff         | je                  0xfffffb44

        $sequence_11 = { e8???????? 8b4004 8b4f24 8b55f8 890c82 e9???????? 8b470c }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8b4004               | mov                 eax, dword ptr [eax + 4]
            //   8b4f24               | mov                 ecx, dword ptr [edi + 0x24]
            //   8b55f8               | mov                 edx, dword ptr [ebp - 8]
            //   890c82               | mov                 dword ptr [edx + eax*4], ecx
            //   e9????????           |                     
            //   8b470c               | mov                 eax, dword ptr [edi + 0xc]

        $sequence_12 = { a5 68000000f0 6a18 a5 83c0e0 33f6 }
            // n = 6, score = 100
            //   a5                   | movsd               dword ptr es:[edi], dword ptr [esi]
            //   68000000f0           | push                0xf0000000
            //   6a18                 | push                0x18
            //   a5                   | movsd               dword ptr es:[edi], dword ptr [esi]
            //   83c0e0               | add                 eax, -0x20
            //   33f6                 | xor                 esi, esi

        $sequence_13 = { 85c0 7888 8bcf e8???????? }
            // n = 4, score = 100
            //   85c0                 | test                eax, eax
            //   7888                 | js                  0xffffff8a
            //   8bcf                 | mov                 ecx, edi
            //   e8????????           |                     

        $sequence_14 = { 33c0 689e000000 668984249c000000 8d84249e000000 53 }
            // n = 5, score = 100
            //   33c0                 | xor                 eax, eax
            //   689e000000           | push                0x9e
            //   668984249c000000     | mov                 word ptr [esp + 0x9c], ax
            //   8d84249e000000       | lea                 eax, [esp + 0x9e]
            //   53                   | push                ebx

        $sequence_15 = { e8???????? 59 85c0 0f841afeffff ffb574feffff e8???????? }
            // n = 6, score = 100
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   85c0                 | test                eax, eax
            //   0f841afeffff         | je                  0xfffffe20
            //   ffb574feffff         | push                dword ptr [ebp - 0x18c]
            //   e8????????           |                     

    condition:
        7 of them and filesize < 4599808
}
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