PDF malware analysis — malicious · 85618135b55d4b9d

MALICIOUS

PDF

21.1 KB

MD5: ede1662ebfd5a1c89cfb2b8acbeb3957 SHA-1: d429936129261b3ec5a607c6e4a59425618b8941 SHA-256: 85618135b55d4b9da9de94d917ceb2310407481c238e7fc4ba30b94d6b8600a5

168 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF sample contains XFA form elements with embedded JavaScript, identified as a heap spray exploit. This script is designed to deobfuscate and execute a payload from a reconstructed URL: "http://yj3120fn.ru:8888/ugauguc?jkaA=4&xcWq=5". The ML classifier strongly indicates maliciousness, and the presence of exploit code points to a delivery mechanism for further malicious activity.

Machine Learning

Nyx PDF Classifier malicious score 0.9950

Heuristics 6

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)
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_off00000bed.js` `52def1a34c111c8287fe2b002734de0b759d73e252474dafbfb205918821a8c8`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0xBED	94998 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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