SYMBOLCOMMON_NAMEaka. SYNONYMS
win.netrepser_keylogger (Back to overview)

Netrepser


There is no description at this point.

References
2017-05-05BitdefenderBogdan Botezatu, Alexandru Maximciuc, Cristina Vatamanu, Adrian Schipur
@online{botezatu:20170505:inside:0cff0e6, author = {Bogdan Botezatu and Alexandru Maximciuc and Cristina Vatamanu and Adrian Schipur}, title = {{Inside Netrepser – a JavaScript-based Targeted Attack}}, date = {2017-05-05}, organization = {Bitdefender}, url = {https://labs.bitdefender.com/2017/05/inside-netrepser-a-javascript-based-targeted-attack/}, language = {English}, urldate = {2020-01-08} } Inside Netrepser – a JavaScript-based Targeted Attack
Netrepser
Yara Rules
[TLP:WHITE] win_netrepser_keylogger_auto (20220516 | Detects win.netrepser_keylogger.)
rule win_netrepser_keylogger_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2022-05-16"
        version = "1"
        description = "Detects win.netrepser_keylogger."
        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.netrepser_keylogger"
        malpedia_rule_date = "20220513"
        malpedia_hash = "7f4b2229e6ae614d86d74917f6d5b41890e62a26"
        malpedia_version = "20220516"
        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 = { 8b11 8955f8 8b45f8 c1e818 }
            // n = 4, score = 200
            //   8b11                 | mov                 edx, dword ptr [ecx]
            //   8955f8               | mov                 dword ptr [ebp - 8], edx
            //   8b45f8               | mov                 eax, dword ptr [ebp - 8]
            //   c1e818               | shr                 eax, 0x18

        $sequence_1 = { 8d8da4fdffff 51 8b95c4fdffff 52 }
            // n = 4, score = 200
            //   8d8da4fdffff         | lea                 ecx, [ebp - 0x25c]
            //   51                   | push                ecx
            //   8b95c4fdffff         | mov                 edx, dword ptr [ebp - 0x23c]
            //   52                   | push                edx

        $sequence_2 = { 50 0fb60d???????? 51 68010040b0 }
            // n = 4, score = 200
            //   50                   | push                eax
            //   0fb60d????????       |                     
            //   51                   | push                ecx
            //   68010040b0           | push                0xb0400001

        $sequence_3 = { ff15???????? 8d4dfc 51 6820000100 6a00 }
            // n = 5, score = 200
            //   ff15????????         |                     
            //   8d4dfc               | lea                 ecx, [ebp - 4]
            //   51                   | push                ecx
            //   6820000100           | push                0x10020
            //   6a00                 | push                0

        $sequence_4 = { 8d55fc 52 8d859cf5ffff 50 e8???????? }
            // n = 5, score = 200
            //   8d55fc               | lea                 edx, [ebp - 4]
            //   52                   | push                edx
            //   8d859cf5ffff         | lea                 eax, [ebp - 0xa64]
            //   50                   | push                eax
            //   e8????????           |                     

        $sequence_5 = { 8b450c 50 6a00 6a00 68???????? }
            // n = 5, score = 200
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   50                   | push                eax
            //   6a00                 | push                0
            //   6a00                 | push                0
            //   68????????           |                     

        $sequence_6 = { 894db0 8b55b0 83c201 8955ac }
            // n = 4, score = 200
            //   894db0               | mov                 dword ptr [ebp - 0x50], ecx
            //   8b55b0               | mov                 edx, dword ptr [ebp - 0x50]
            //   83c201               | add                 edx, 1
            //   8955ac               | mov                 dword ptr [ebp - 0x54], edx

        $sequence_7 = { 83c408 a3???????? 8b5508 52 a1???????? }
            // n = 5, score = 200
            //   83c408               | add                 esp, 8
            //   a3????????           |                     
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   52                   | push                edx
            //   a1????????           |                     

        $sequence_8 = { 8d542408 52 ffd1 8904bd70584000 8b4c2448 }
            // n = 5, score = 100
            //   8d542408             | lea                 edx, [esp + 8]
            //   52                   | push                edx
            //   ffd1                 | call                ecx
            //   8904bd70584000       | mov                 dword ptr [edi*4 + 0x405870], eax
            //   8b4c2448             | mov                 ecx, dword ptr [esp + 0x48]

        $sequence_9 = { 8bc5 83e80a f7d8 1bc0 23c7 5f 8935???????? }
            // n = 7, score = 100
            //   8bc5                 | mov                 eax, ebp
            //   83e80a               | sub                 eax, 0xa
            //   f7d8                 | neg                 eax
            //   1bc0                 | sbb                 eax, eax
            //   23c7                 | and                 eax, edi
            //   5f                   | pop                 edi
            //   8935????????         |                     

        $sequence_10 = { c74424086d5f6d6f 8944240c 89442410 c744241400000000 }
            // n = 4, score = 100
            //   c74424086d5f6d6f     | mov                 dword ptr [esp + 8], 0x6f6d5f6d
            //   8944240c             | mov                 dword ptr [esp + 0xc], eax
            //   89442410             | mov                 dword ptr [esp + 0x10], eax
            //   c744241400000000     | mov                 dword ptr [esp + 0x14], 0

        $sequence_11 = { 7516 e8???????? 8d442410 50 56 e8???????? 85c0 }
            // n = 7, score = 100
            //   7516                 | jne                 0x18
            //   e8????????           |                     
            //   8d442410             | lea                 eax, [esp + 0x10]
            //   50                   | push                eax
            //   56                   | push                esi
            //   e8????????           |                     
            //   85c0                 | test                eax, eax

        $sequence_12 = { 8b8c243c010000 5f 5e 8bc3 5b 33cc e8???????? }
            // n = 7, score = 100
            //   8b8c243c010000       | mov                 ecx, dword ptr [esp + 0x13c]
            //   5f                   | pop                 edi
            //   5e                   | pop                 esi
            //   8bc3                 | mov                 eax, ebx
            //   5b                   | pop                 ebx
            //   33cc                 | xor                 ecx, esp
            //   e8????????           |                     

        $sequence_13 = { 8d0424 50 51 c7442408536c6565 c744240c70000000 ff15???????? a3???????? }
            // n = 7, score = 100
            //   8d0424               | lea                 eax, [esp]
            //   50                   | push                eax
            //   51                   | push                ecx
            //   c7442408536c6565     | mov                 dword ptr [esp + 8], 0x65656c53
            //   c744240c70000000     | mov                 dword ptr [esp + 0xc], 0x70
            //   ff15????????         |                     
            //   a3????????           |                     

        $sequence_14 = { 50 51 c744240846696e64 c744240c5265736f c744241075726365 }
            // n = 5, score = 100
            //   50                   | push                eax
            //   51                   | push                ecx
            //   c744240846696e64     | mov                 dword ptr [esp + 8], 0x646e6946
            //   c744240c5265736f     | mov                 dword ptr [esp + 0xc], 0x6f736552
            //   c744241075726365     | mov                 dword ptr [esp + 0x10], 0x65637275

        $sequence_15 = { 5f 8b0d???????? 8d0424 50 51 c74424084f70656e }
            // n = 6, score = 100
            //   5f                   | pop                 edi
            //   8b0d????????         |                     
            //   8d0424               | lea                 eax, [esp]
            //   50                   | push                eax
            //   51                   | push                ecx
            //   c74424084f70656e     | mov                 dword ptr [esp + 8], 0x6e65704f

    condition:
        7 of them and filesize < 303104
}
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