PDF malware analysis — malicious · fbf66ccd43db6a2e

MALICIOUS

PDF

7.4 KB

MD5: deb166ee1928a246e8d70cbb34b3972b SHA-1: 839381c7ae616cfae09a3867f4d1467b4debd7d7 SHA-256: fbf66ccd43db6a2e9d36bb2044f4ac2657756ecd923e5f9674efbe133cb1730e

178 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File: User Execution T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains XFA form elements which are known to be vulnerable to heap spray attacks. The heuristic PDF_XFA_HEAP_SPRAY indicates exploit code was found within a decoded stream. Additionally, a high-severity heuristic, PDF_XFA_SCRIPT, confirms the presence of risky executable script within the XFA form. The ML classifier also strongly flagged this PDF as malicious. The embedded JavaScript file, stream_000_off00000051.js, likely contains the payload for the heap spray, aiming to download and execute a second-stage malicious artifact.

Machine Learning

Nyx PDF Classifier malicious score 0.9990

Heuristics 8

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.
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.
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)
ASCII85Decode filter (with exploit indicators) low PDF_FILTER_85

ASCII85 encoding filter present alongside exploit delivery indicators — uncommon outside of obfuscation
PDF differential parser failed info PDF_DIFFERENTIAL_PARSE_FAILED

The cross-check parser (pdfminer.six) failed on this file: PDF differential parser failed: PSSyntaxError. Static heuristics still ran and any of their findings above are valid; only the differential cross-check signal is missing.
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`stream_000_off00000051.js` `0e29cecd13c31492826be8a508974cc2be3cfdea2773ca88ddc5c1a52551a901`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x51	15424 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

Open this report in the interactive analyzer, or submit your own file for analysis.