Office (OOXML) / .XLSM malware analysis — malicious · ace3a764ec8da4bf

MALICIOUS

Office (OOXML) / .XLSM

139.4 KB Created: 2020-07-05 12:37:33 UTC Authoring application: Microsoft Excel 16.0300

MD5: 1b8ea7e30bf66c89d5260ee521560dfd SHA-1: b43054fdad6f340963086f025c423b4d802a150b SHA-256: ace3a764ec8da4bfed78cbbf5d6facb8612178967feb186ef1f6a32f4cf85fce

380 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

This XLSM file contains a Workbook_Open macro that utilizes WScript.Shell and the Shell() function to execute arbitrary commands. The ClamAV detection 'Xls.Downloader.Obfuse-9382072-0' strongly suggests a downloader functionality, likely intended to fetch and execute a second-stage payload. The presence of VBA macros and the use of Shell() are key indicators of this malicious behavior.

Heuristics 8

Shell() call in VBA critical OLE_VBA_SHELL

Shell() call in VBA
WScript.Shell usage critical OLE_VBA_WSCRIPT

WScript.Shell usage
ClamAV: Xls.Downloader.Obfuse-9382072-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.Obfuse-9382072-0
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
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` `f6121f767364880de172c41ef778fac733f495cc3648b161da7561e46d4c1359`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1585 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.
`vbaProject_00.bin` `d76bd0a7fdf1140cf42c808ff9fbd42702c3c211c17c2b3fbc7fc95b1bab0809`	vba-project	OOXML VBA project: xl/vbaProject.bin	14848 bytes
Detection ClamAV: Xls.Downloader.Obfuse-9382072-0 Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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