Office (OOXML) / .XLSM malware analysis — malicious · c8f3d97c54386b86

MALICIOUS

Office (OOXML) / .XLSM

64.4 KB Created: 2021-05-04 11:57:17 UTC Authoring application: Microsoft Excel 15.0300

MD5: dc48640ca8488d4c4e61b807ef19d11c SHA-1: e2cfbc565e62b269a7bfbdf2b3c060e52aaa6614 SHA-256: c8f3d97c54386b86778a1d20917353583bcf706ffe0615d962683d55e449bcab

268 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The OOXML file contains VBA macros, specifically a Workbook_Open macro designed to execute arbitrary code. The critical heuristic 'OLE_VBA_ASC_CHR_SHIFT_SHELL' indicates that the macro uses character-shifting techniques to obfuscate a Shell command, which is then executed. This pattern suggests the document is a malicious macro-enabled file designed to download and execute a second-stage payload.

Heuristics 7

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
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
Environ() call (env variable access) low OLE_VBA_ENVIRON

Environ() call (env variable access)

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `9ccc9c01f2f1d3605059371c896051a10b40e7db4e89eb1790e044953e4d2e81`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	2007 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` `f9f909949a9f6bc57ec433ef803bc7ce3cf747fe78bb6eb8b914af2be93843f5`	vba-project	OOXML VBA project: xl/vbaProject.bin	14848 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.

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