Xls.Dropper.Agent-7771147-0 Office (OOXML) / .XLSX malware analysis — malicious · 284792b49362e6b0

MALICIOUS

Office (OOXML) / .XLSX

381.5 KB Created: 2020-05-05 20:43:50 UTC Authoring application: Microsoft Excel 16.0300

MD5: 75de10330d362538600564fa924cbe1e SHA-1: 626c972791ecf9b7f58b71965b142ce3c08572e4 SHA-256: 284792b49362e6b051024b7a41aaefeb634d27fd2032e6be38531eda09671aef

380 Risk Score

Malware Insights

Xls.Dropper.Agent-7771147-0 · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file is an Excel spreadsheet containing a Workbook_Open macro. This macro utilizes character-shifting techniques with VBA functions like Asc, Chr, and Mid to decode and execute a command via Shell(). This is a common pattern for macro-based malware droppers. The ClamAV detection name 'Xls.Dropper.Agent-7771147-0' further supports this assessment. The script's primary intent is to download and execute a second-stage payload.

Heuristics 9

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.
ClamAV: Xls.Dropper.Agent-7771147-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Dropper.Agent-7771147-0
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
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://schemas.openxmlformats.org/spreadsheetml/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
- http://schemas.microsoft.com/office/spreadsheetml/2014/revision
- http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
- http://schemas.microsoft.com/office/spreadsheetml/2016/revision3

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `4323cf2bb89cd5565b9adeca1e6e65a58b71694d1a30dbd1a496f8d5db968705`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	2023 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` `c6d01504c7fb6dac6afb22f71f63fda47ed5156a7774177cb8c8f5ae53d5128b`	vba-project	OOXML VBA project: xl/vbaProject.bin	16384 bytes
Detection ClamAV: Xls.Dropper.Agent-7771147-0 Obfuscation or payload: likely Carved macro source contains an auto-exec entry point and execution/download terms.

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