Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 1f156f86d45e28da…

MALICIOUS

Office (OLE) / .XLSX

830.0 KB Created: 2020-03-23 14:19:10 Authoring application: Microsoft Excel First seen: 2022-07-11
MD5: 0c09fbdf98f0a6144a42fde00fe21504 SHA-1: bb4a594ecf90ed6b9e408c404b08620500fb4c02 SHA-256: 1f156f86d45e28dac74015051546305497adb86b4e46bb7d9a84ccf5e25a12f4
342 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols T1059.001 PowerShell T1059.003 Windows Command Shell

The sample contains Excel 4.0 macros, including an Auto_Open function that utilizes dangerous APIs like RUN. It also references the URLDownloadToFile API, indicating an intent to download a payload from the embedded URL http://0b.htb/s.dll. The presence of environment evasion techniques suggests a deliberate attempt to hinder analysis.

Heuristics 8

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • ClamAV: Xls.Dropper.Agent-7781312-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7781312-0
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • XLM Auto_Open environment-evasion HALT gate high OLE_XLM_ENVIRONMENT_EVASION_HALT
    Excel 4.0 macro sheet auto-executes multiple GET.WORKSPACE / GET.WINDOW environment checks and halts execution when the host does not match the expected user environment. This is a common sandbox-evasion pattern in XLM malware and is stronger than a bare XLM macro-sheet indicator.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • 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://0b.htb/s.dll�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a8770f019793b6e706ca3f4c1f5502c43e46243f69ef72f9407612d4d447dac8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2017335 bytes

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