Office (OLE) / .XLS malware analysis — malicious · 2ae901ef60f49605

MALICIOUS

Office (OLE) / .XLS

35.0 KB Created: 2021-08-18 21:45:08 Authoring application: Microsoft Excel

MD5: 5355b7b95be40024d17e60c9434f378b SHA-1: 4ecba6fcc9925861289efc1a8be4a4751315ebef SHA-256: 2ae901ef60f496052b1fd138bfa5c1cee5860ab20d2095c3cc0944458efd51cd

200 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell

The sample is an Excel 4.0 macro-enabled spreadsheet that uses an Auto_Open macro to execute a command. The macro constructs and runs a curl command to download a DLL payload from 'https://bizcomtech.com/rob122DzjsdFA.dll' and saves it as 'c:\users\public\cdnupdater.png'. It then attempts to execute this downloaded file. The use of XLM macros and the specific download/execution pattern are indicative of a downloader.

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.
Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `2ae8799f732ae02478a8ebca8c6eb412a6d1e79f21fbacbcc8a880b099766c8d`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3746 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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