Office (OOXML) / .XLSX malware analysis — malicious · c84b1478fdf53dd0

MALICIOUS

Office (OOXML) / .XLSX

83.1 KB Created: 2021-03-04 04:01:39 UTC Authoring application: Microsoft Excel 16.0300

MD5: bf2543c69187a3df2f852028e1eba429 SHA-1: c0affc945487648d9c1c10e2c6f29fb2122e3734 SHA-256: c84b1478fdf53dd00791f5ceb8e7744493964c363a8c02ea4f24600dab28fb83

220 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell

The file is an Excel spreadsheet containing a Workbook_Open macro that uses character-shifting functions to decode and execute a command via Shell(). This indicates a macro-based execution technique designed to download and run a second-stage payload.

Heuristics 5

Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
VBA character-shift decoded Shell command critical OLE_VBA_ASC_CHR_SHIFT_SHELL

VBA auto-exec macro stores an encoded command string, decodes it with a Mid/Asc/Chr character-shift loop, and passes the recovered text to Shell. This is a high-confidence command stager.
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.
VBA project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `eb414e6c4356c16371be612ca37da1c9f566fb7fe31eea831e9fddaf47c953fe`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	19697 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `20ca0c64bd4ed2c585b196275a3ecc5c35feeadf4d33b67bda57fbb07a65c2b0`	vba-project	OOXML VBA project: xl/vbaProject.bin	29184 bytes

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