SYMBOLCOMMON_NAMEaka. SYNONYMS
win.stealbit (Back to overview)

StealBit

aka: Corrempa

This is a stealer used by LockBit 2.0.

References
2022-06-28AccentureAccenture
@online{accenture:20220628:stealbit:ec9bb0e, author = {Accenture}, title = {{Steal(Bit) or exfil, what does it (Ex)Matter? Comparative Analysis of Custom Exfiltration Tools}}, date = {2022-06-28}, organization = {Accenture}, url = {https://www.accenture.com/us-en/blogs/security/stealbit-exmatter-exfiltration-tool-analysis}, language = {English}, urldate = {2022-09-26} } Steal(Bit) or exfil, what does it (Ex)Matter? Comparative Analysis of Custom Exfiltration Tools
ExMatter StealBit
2022-05-11KasperskyGReAT
@online{great:20220511:new:a56bc90, author = {GReAT}, title = {{New ransomware trends in 2022}}, date = {2022-05-11}, organization = {Kaspersky}, url = {https://securelist.com/new-ransomware-trends-in-2022/106457/}, language = {English}, urldate = {2022-05-17} } New ransomware trends in 2022
BlackCat Conti DEADBOLT DoubleZero LockBit PartyTicket StealBit
2021-12-16CybereasonAleksandar Milenkoski, Kotaro Ogino
@online{milenkoski:20211216:inside:40c2e51, author = {Aleksandar Milenkoski and Kotaro Ogino}, title = {{Inside the LockBit Arsenal - The StealBit Exfiltration Tool}}, date = {2021-12-16}, organization = {Cybereason}, url = {https://www.cybereason.com/blog/threat-analysis-report-inside-the-lockbit-arsenal-the-stealbit-exfiltration-tool}, language = {English}, urldate = {2022-02-04} } Inside the LockBit Arsenal - The StealBit Exfiltration Tool
LockBit StealBit
2021-09-24YoroiLuigi Martire, Luca Mella
@online{martire:20210924:hunting:d29a5e6, author = {Luigi Martire and Luca Mella}, title = {{Hunting the LockBit Gang's Exfiltration Infrastructures}}, date = {2021-09-24}, organization = {Yoroi}, url = {https://yoroi.company/research/hunting-the-lockbit-gangs-exfiltration-infrastructures/}, language = {English}, urldate = {2021-09-24} } Hunting the LockBit Gang's Exfiltration Infrastructures
LockBit StealBit
2021-08-12Twitter (@r3c0nst)Frank Boldewin
@online{boldewin:20210812:stealbit:08f3307, author = {Frank Boldewin}, title = {{Tweet on StealBit malware as used by LockBit 2.0}}, date = {2021-08-12}, organization = {Twitter (@r3c0nst)}, url = {https://twitter.com/r3c0nst/status/1425875923606310913}, language = {English}, urldate = {2021-08-16} } Tweet on StealBit malware as used by LockBit 2.0
StealBit
Yara Rules
[TLP:WHITE] win_stealbit_auto (20230125 | Detects win.stealbit.)
rule win_stealbit_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.stealbit."
        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.stealbit"
        malpedia_rule_date = "20230124"
        malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686"
        malpedia_version = "20230125"
        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 = { 894104 83c108 3b4d08 72ec 5d c3 e8???????? }
            // n = 7, score = 300
            //   894104               | mov                 dword ptr [ecx + 4], eax
            //   83c108               | add                 ecx, 8
            //   3b4d08               | cmp                 ecx, dword ptr [ebp + 8]
            //   72ec                 | jb                  0xffffffee
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   e8????????           |                     

        $sequence_1 = { e8???????? 8d1c4502000000 8bcb e8???????? 8bf8 85ff 740b }
            // n = 7, score = 300
            //   e8????????           |                     
            //   8d1c4502000000       | lea                 ebx, [eax*2 + 2]
            //   8bcb                 | mov                 ecx, ebx
            //   e8????????           |                     
            //   8bf8                 | mov                 edi, eax
            //   85ff                 | test                edi, edi
            //   740b                 | je                  0xd

        $sequence_2 = { 894204 8bc2 5d c20400 8bd1 }
            // n = 5, score = 300
            //   894204               | mov                 dword ptr [edx + 4], eax
            //   8bc2                 | mov                 eax, edx
            //   5d                   | pop                 ebp
            //   c20400               | ret                 4
            //   8bd1                 | mov                 edx, ecx

        $sequence_3 = { 5f 0f99c1 5e 8bc1 5b 5d c3 }
            // n = 7, score = 300
            //   5f                   | pop                 edi
            //   0f99c1               | setns               cl
            //   5e                   | pop                 esi
            //   8bc1                 | mov                 eax, ecx
            //   5b                   | pop                 ebx
            //   5d                   | pop                 ebp
            //   c3                   | ret                 

        $sequence_4 = { 3d8217677e 740b 46 3bf7 75e4 33c0 5f }
            // n = 7, score = 300
            //   3d8217677e           | cmp                 eax, 0x7e671782
            //   740b                 | je                  0xd
            //   46                   | inc                 esi
            //   3bf7                 | cmp                 esi, edi
            //   75e4                 | jne                 0xffffffe6
            //   33c0                 | xor                 eax, eax
            //   5f                   | pop                 edi

        $sequence_5 = { 59 85c0 0f8438040000 57 8d9504ffffff }
            // n = 5, score = 300
            //   59                   | pop                 ecx
            //   85c0                 | test                eax, eax
            //   0f8438040000         | je                  0x43e
            //   57                   | push                edi
            //   8d9504ffffff         | lea                 edx, [ebp - 0xfc]

        $sequence_6 = { 660f6fc2 660f73db02 660f73fa0e 660febda 660fe75c0f10 83c120 }
            // n = 6, score = 300
            //   660f6fc2             | movdqa              xmm0, xmm2
            //   660f73db02           | psrldq              xmm3, 2
            //   660f73fa0e           | pslldq              xmm2, 0xe
            //   660febda             | por                 xmm3, xmm2
            //   660fe75c0f10         | movntdq             xmmword ptr [edi + ecx + 0x10], xmm3
            //   83c120               | add                 ecx, 0x20

        $sequence_7 = { 663bc6 7444 663bc7 743f 663bc3 743a 663bc1 }
            // n = 7, score = 300
            //   663bc6               | cmp                 ax, si
            //   7444                 | je                  0x46
            //   663bc7               | cmp                 ax, di
            //   743f                 | je                  0x41
            //   663bc3               | cmp                 ax, bx
            //   743a                 | je                  0x3c
            //   663bc1               | cmp                 ax, cx

        $sequence_8 = { 58 6a6f 6689458c 58 6a7a 6689458e 58 }
            // n = 7, score = 300
            //   58                   | pop                 eax
            //   6a6f                 | push                0x6f
            //   6689458c             | mov                 word ptr [ebp - 0x74], ax
            //   58                   | pop                 eax
            //   6a7a                 | push                0x7a
            //   6689458e             | mov                 word ptr [ebp - 0x72], ax
            //   58                   | pop                 eax

        $sequence_9 = { 6a73 6689bdd0feffff 6689bda4feffff 5f 6a2e 668985acfeffff 58 }
            // n = 7, score = 300
            //   6a73                 | push                0x73
            //   6689bdd0feffff       | mov                 word ptr [ebp - 0x130], di
            //   6689bda4feffff       | mov                 word ptr [ebp - 0x15c], di
            //   5f                   | pop                 edi
            //   6a2e                 | push                0x2e
            //   668985acfeffff       | mov                 word ptr [ebp - 0x154], ax
            //   58                   | pop                 eax

    condition:
        7 of them and filesize < 131072
}
[TLP:WHITE] win_stealbit_w0   (20210818 | Detects Stealbit used by Lockbit 2.0 Ransomware Gang)
rule win_stealbit_w0 {
	meta:
		description = "Detects Stealbit used by Lockbit 2.0 Ransomware Gang"
		author = "Frank Boldewin (@r3c0nst)"
		reference = "https://raw.githubusercontent.com/fboldewin/YARA-rules/master/Lockbit2.Stealbit.yar"
		date = "2021-08-12"
		hash1 = "3407f26b3d69f1dfce76782fee1256274cf92f744c65aa1ff2d3eaaaf61b0b1d"
		hash2 = "bd14872dd9fdead89fc074fdc5832caea4ceac02983ec41f814278130b3f943e"

        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.stealbit"
        malpedia_rule_date = "20210818"
        malpedia_hash = ""
        malpedia_version = "20210818"
        malpedia_license = "CC BY-SA 4.0"
        malpedia_sharing = "TLP:WHITE"

	strings:
		$C2Decryption = {33 C9 8B C1 83 E0 0F 8A 80 ?? ?? ?? ?? 30 81 ?? ?? ?? ?? 41 83 F9 7C 72 E9 E8}
		
	condition:
		uint16(0) == 0x5A4D and filesize < 100KB and $C2Decryption
}
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