Office (OLE) malware analysis — malicious · a27acc537911ec9f

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-27 11:43:35 Authoring application: Microsoft Excel

MD5: 707c4e2f5be28520ba726fa41c4934a5 SHA-1: a31f6e79f406a22c4652965dfd58cbe819e624c8 SHA-256: a27acc537911ec9f3968222eae6f7c72d4af44dc056a42e50172df1096b2a432

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating potential malicious execution. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands, likely to download and run a second-stage payload. The macro sheet itself is obfuscated, making detailed analysis of the exact commands difficult, but the intent is clear.

Heuristics 3

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.
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `56250ef5c2fb75125ab79671796e5bdaa5b39ee4c890552f37c789bd40eb7f51`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6882 bytes

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