Office (OLE) / .XLSX malware analysis — malicious · 7d7f9477110643a6

MALICIOUS

Office (OLE) / .XLSX

167.0 KB Created: 2020-02-27 10:23:09 Authoring application: Microsoft Excel First seen: 2022-08-04

MD5: b5d469a07709b5ca6fee934b1e5e8e38 SHA-1: a6265d96a7cf33612dc5286e0e91f8ee21909d8c SHA-256: 7d7f9477110643a6f9065cc9ed67440aa091e323ba6b981c1fb504fdd797535c

200 Risk Score

Malware Insights

MITRE ATT&CK

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. The macro utilizes dangerous formula APIs, including the RUN function, indicating an intent to execute arbitrary commands. This is further supported by the ShellExecute API reference. The macro likely serves as a downloader for a second-stage 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.
Reference to ShellExecute API high SC_STR_SHELLEXEC

Reference to ShellExecute API
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` `44fa88fb92f54e6f34fd7d82e2a7b4f7d3499d8951cda281ed3cbe4aaba65aaf`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	21332 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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