SYMBOLCOMMON_NAMEaka. SYNONYMS
win.felismus (Back to overview)

Felismus

Actor(s): Sowbug


There is no description at this point.

References
2017-11-07SymantecSymantec Security Response
@online{response:20171107:sowbug:7f0d6eb, author = {Symantec Security Response}, title = {{Sowbug: Cyber espionage group targets South American and Southeast Asian governments}}, date = {2017-11-07}, organization = {Symantec}, url = {https://www.symantec.com/connect/blogs/sowbug-cyber-espionage-group-targets-south-american-and-southeast-asian-governments}, language = {English}, urldate = {2019-12-17} } Sowbug: Cyber espionage group targets South American and Southeast Asian governments
Felismus StarLoader Sowbug
Yara Rules
[TLP:WHITE] win_felismus_auto (20220411 | Detects win.felismus.)
rule win_felismus_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-04-08"
        version = "1"
        description = "Detects win.felismus."
        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.felismus"
        malpedia_rule_date = "20220405"
        malpedia_hash = "ecd38294bd47d5589be5cd5490dc8bb4804afc2a"
        malpedia_version = "20220411"
        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 = { 8bfe 53 8b1d???????? 68???????? 56 f3ab ffd3 }
            // n = 7, score = 100
            //   8bfe                 | mov                 edi, esi
            //   53                   | push                ebx
            //   8b1d????????         |                     
            //   68????????           |                     
            //   56                   | push                esi
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   ffd3                 | call                ebx

        $sequence_1 = { c744241408000000 7514 8d8c24a8030000 51 e8???????? 83c404 84c0 }
            // n = 7, score = 100
            //   c744241408000000     | mov                 dword ptr [esp + 0x14], 8
            //   7514                 | jne                 0x16
            //   8d8c24a8030000       | lea                 ecx, dword ptr [esp + 0x3a8]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   84c0                 | test                al, al

        $sequence_2 = { c60000 6a11 ff15???????? 8bf0 }
            // n = 4, score = 100
            //   c60000               | mov                 byte ptr [eax], 0
            //   6a11                 | push                0x11
            //   ff15????????         |                     
            //   8bf0                 | mov                 esi, eax

        $sequence_3 = { 52 ffd6 8b4514 8b35???????? 50 }
            // n = 5, score = 100
            //   52                   | push                edx
            //   ffd6                 | call                esi
            //   8b4514               | mov                 eax, dword ptr [ebp + 0x14]
            //   8b35????????         |                     
            //   50                   | push                eax

        $sequence_4 = { 1bc0 83d8ff 3bc3 7451 bf???????? }
            // n = 5, score = 100
            //   1bc0                 | sbb                 eax, eax
            //   83d8ff               | sbb                 eax, -1
            //   3bc3                 | cmp                 eax, ebx
            //   7451                 | je                  0x53
            //   bf????????           |                     

        $sequence_5 = { 66ab aa b9ff000000 33c0 8dbc2415010000 }
            // n = 5, score = 100
            //   66ab                 | stosw               word ptr es:[edi], ax
            //   aa                   | stosb               byte ptr es:[edi], al
            //   b9ff000000           | mov                 ecx, 0xff
            //   33c0                 | xor                 eax, eax
            //   8dbc2415010000       | lea                 edi, dword ptr [esp + 0x115]

        $sequence_6 = { f3ab ffd3 68???????? 56 ff15???????? 68ff000000 8bf8 }
            // n = 7, score = 100
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   ffd3                 | call                ebx
            //   68????????           |                     
            //   56                   | push                esi
            //   ff15????????         |                     
            //   68ff000000           | push                0xff
            //   8bf8                 | mov                 edi, eax

        $sequence_7 = { 6888130000 ff15???????? 57 ffd3 8bf0 83c404 85f6 }
            // n = 7, score = 100
            //   6888130000           | push                0x1388
            //   ff15????????         |                     
            //   57                   | push                edi
            //   ffd3                 | call                ebx
            //   8bf0                 | mov                 esi, eax
            //   83c404               | add                 esp, 4
            //   85f6                 | test                esi, esi

        $sequence_8 = { 50 ffd7 6a04 6800100000 6814030000 6a00 56 }
            // n = 7, score = 100
            //   50                   | push                eax
            //   ffd7                 | call                edi
            //   6a04                 | push                4
            //   6800100000           | push                0x1000
            //   6814030000           | push                0x314
            //   6a00                 | push                0
            //   56                   | push                esi

        $sequence_9 = { 8d942414010000 68???????? 52 ffd6 8d842414010000 8d8c241c030000 }
            // n = 6, score = 100
            //   8d942414010000       | lea                 edx, dword ptr [esp + 0x114]
            //   68????????           |                     
            //   52                   | push                edx
            //   ffd6                 | call                esi
            //   8d842414010000       | lea                 eax, dword ptr [esp + 0x114]
            //   8d8c241c030000       | lea                 ecx, dword ptr [esp + 0x31c]

    condition:
        7 of them and filesize < 204800
}
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