Office (OLE) malware analysis — malicious · a0f4e34c275998e8

MALICIOUS

Office (OLE)

317.7 KB Created: 1999-12-24 16:36:33 Authoring application: Microsoft Excel

MD5: 84c14d70744a942353c095a3fc82521d SHA-1: 98cf21fda88cbdd3bf181be349dc90d9feb8c188 SHA-256: a0f4e34c275998e8798dd5c29efb4f7f2e100ad10d453e1ecbfaffebfdbc3f5a

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1059.003 Windows Command Shell T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information

The file is an Excel document containing both VBA and XLM macros, with a Workbook_Open macro triggering the execution. Heuristics indicate XOR-encoded strings and an appended payload, suggesting the macros are used to deobfuscate and execute further malicious code. The presence of an appended executable-looking payload and the Workbook_Open trigger strongly suggest a downloader or droppper functionality.

Heuristics 7

XOR-encoded strings (key 0x59) critical SC_XOR_ENCODED

Found 7 Windows library/API name(s) XOR-encoded with single-byte key 0x59: 'LoadLibraryA', 'GetProcAddress', 'VirtualAlloc', 'CreateProcessA', 'ExitProcess', 'CreateFileA', 'CreateThread'
OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY

OLE file is 325,308 bytes but its declared streams total only 184,311 bytes — 140,997 bytes (43%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD

OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
Suspicious extracted artifact high 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.
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.
VBA macros detected medium OLE_VBA_MACROS

Document contains VBA macro code

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `c2d076a6e609a8b33579240c4c97ddb741702fb224c691665176231441d0ac2f`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	17509 bytes
`macros.bas` `eb4d64633dbbdf499c4c427f54bcbb8d617bb7ac839c1a0e496abd6eef69da23`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	27429 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 30 Chr/ChrW string-construction calls.

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