Office (OOXML) / .XLSM malware analysis — malicious · 3d23bb0fbd0b7040

MALICIOUS

Office (OOXML) / .XLSM

12.9 KB Created: 2020-09-20 21:17:44 UTC Authoring application: Microsoft Excel 16.0300

MD5: e309fc8f99a6906a80e85a7b9bd02296 SHA-1: acc21cdbe0c7b4db72f788858663b33b2c7d03b3 SHA-256: 3d23bb0fbd0b70409765da5888f3e37b4ace5cd9171265acf7a793d428107abe

230 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

The sample is an XLSM file containing Excel 4.0 macros. The macros utilize the dangerous EXEC function to download a second-stage payload from 'http://iurl.vip/pbh2t' to '%Temp%\SrFHP.exe' and then execute it. The document also contains a lure instructing the user to enable macros, which is a common technique for malware delivery.

Heuristics 7

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks.
Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME

Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
Dangerous XLM formula APIs: EXEC critical OOXML_XLM_DANGEROUS_FN

Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
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
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.
Hidden worksheet (veryHidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://iurl.vip/pbh2t
- http://schemas.openxmlformats.org/spreadsheetml/2006/main
- http://schemas.microsoft.com/office/excel/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/relationships
- http://schemas.openxmlformats.org/markup-compatibility/2006
- http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `eef33da28600f3e552e21310167c2901dbdbc397fa4f2ca02863059134e8a760`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	1637 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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