Office (OOXML) malware analysis — malicious · bde9c5e731afdfc9

MALICIOUS

Office (OOXML)

17.5 KB Created: 2021-08-26 00:54:24 UTC Authoring application: Microsoft Excel 15.0300

MD5: f8ae702d7ae6c32e2d539236ab7282ec SHA-1: db7cee79dd755cda162c4f17bff33c4dd0a11b65 SHA-256: bde9c5e731afdfc997d665820dff30c8cd8d35b743b1c2631f47763083fdd8b1

322 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols

The sample is an Office document containing obfuscated VBA macros designed to execute automatically upon opening. The Workbook_Open macro triggers the execution of shell commands and object creation, indicative of a downloader or dropper. The obfuscated code likely attempts to fetch and run a secondary payload, though the exact URL is not directly visible due to heavy obfuscation.

Heuristics 8

Shell() call in VBA critical OLE_VBA_SHELL

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

WScript.Shell usage
Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER

Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC

Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
VBA project inside OOXML medium OOXML_VBA

Document contains a VBA project — VBA macros present
Suspicious extracted artifact info 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `3b80ee4932dcc30f5d90b143cdfe33dc58921587174441316abc3afca09f92c9`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	5626 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 7 long base64-like blob(s).
`vbaProject_00.bin` `786c0cdfea2430eb193c4eb80e52ef8c534ccab0ef98b89b3d30cb26e64d7c6d`	vba-project	OOXML VBA project: xl/vbaProject.bin	22528 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 7 long base64-like blob(s).

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