Office (OLE) malware analysis — malicious · fc240a4499374f10

MALICIOUS

Office (OLE)

396.1 KB

MD5: a6e2100f211506c6ede04f141adf41d4 SHA-1: 67881282b18d46e87fb2724356f7aac9e2a35707 SHA-256: fc240a4499374f10ba5dcc7e62be8b02eda05cc2eab55b9db0cdf76db756d25a

298 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The sample is identified as a malicious PDF dropper by ClamAV. Static analysis reveals the presence of XFA forms and JavaScript, specifically utilizing String.fromCharCode and heap-spray techniques, indicating an attempt to execute arbitrary code. The embedded PDF artifact and the decompressed JavaScript stream are key indicators of this malicious behavior. The primary function appears to be the download and execution of a second-stage payload.

Heuristics 9

XFA form contains risky executable script high CVE related PDF_XFA_SCRIPT

PDF embeds an XFA form whose script block contains exploit, submission/launch, or shell-execution primitives. Ordinary LiveCycle print/update scripts are left as generic XFA/JS signals unless stronger behavior is present.
Secondary embedded PDF body has suspicious static findings critical POLYGLOT_CHILD_PDF_STATIC_TRIAGE

A valid PDF body was found at a nonzero offset inside another container and its carved contents matched PDF exploit or lure heuristics. This catches polyglots where the top-level magic routes to ZIP/OLE while a PDF reader or downstream parser opens the hidden PDF payload.
XFA JavaScript heap-spray exploit code critical PDF_XFA_HEAP_SPRAY

PDF contains XFA script content with heap-spray or shellcode-like JavaScript markers such as large encoded word sequences, util.pack, large arrays, or spray variable names. This is a weaponised Adobe Reader exploit pattern, not a normal interactive form.
ClamAV: Pdf.Dropper.Agent-7327780-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Dropper.Agent-7327780-0
OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY

OLE file is 405,599 bytes but its declared streams total only 0 bytes — 405,599 bytes (100%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
XFA form low PDF_XFA

PDF uses XML Forms Architecture — can contain script logic
String.fromCharCode low PDF_FROMCHARCODE

String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
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
`stream_000_off00000049.js` `0372351f0cb4c23e2ed02ac76db367f727b4464fc4d8fed4166853716cbd9c4f`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x49	4194304 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s).
`polyglot_child_pdf_off000003e8.pdf` `239011a203076530cd2f05d4a2c9e9c4eeb8a36549b3eb170c77c9510100fdee`	polyglot-child-pdf	Secondary PDF body inside ole container at offset 0x3E8	404599 bytes

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