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

Static analysis result for SHA-256 4aa6cb24f72630f0…

MALICIOUS

Office (OLE) / .XLS

43.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 35c9a9ad8d3f5cefc8cefec6b6c1ea24 SHA-1: 72549264fd8f4736f9010c044b46ab30ee972c01 SHA-256: 4aa6cb24f72630f02a70e613e03d9f071d931dfe064231dfcd1f845347b9eb35
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1218.011 System Binary Proxy Execution: Rundll32 T1566.001 Phishing: Spearphishing Attachment

The sample is an Excel 4.0 macro-enabled spreadsheet designed to trick users into enabling macros. Upon enabling, it executes an Auto_Open macro that uses `rundll32.exe` with the `DllRegisterServer` entry point. The macro also attempts to download a file from the URL `http://mcs.ihdf.org/bxdskxok/` and constructs a path `..\\\AppData\\\\Roaming\\\\Goka.` which likely indicates the intended location for the downloaded payload.

Heuristics 5

  • 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.
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b68def77bf3d78b7c0be9f30ad60574365101f4a762f9255957bf746dbc07ff7		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1729 bytes

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