Malicious PDF — malware analysis report

Static analysis result for SHA-256 54077a5b15638e35…

MALICIOUS

PDF

312.6 KB Authoring application: PyMuPDF First seen: 2026-04-09
MD5: 522cda0c18b410daa033dc66c48eb75a SHA-1: dafd571da1df72fb53bcd250e8b901103b51d6e4 SHA-256: 54077a5b15638e354fa02318623775b7a1cc0e8c21e59bcbab333035369e377f
194 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

This PDF is flagged as malicious by both ClamAV and an ML classifier, specifically due to the presence of embedded JavaScript and an exploit targeting CVE-2026-34621. The embedded JavaScript, particularly the 'acroform_b64_00.js' script, is heavily obfuscated but appears to be designed to download and execute a second-stage payload from a remote source. The presence of suspicious URLs further supports this malicious intent. The exploit chain indicates a high likelihood of this PDF being used as a dropper for further malware.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9031

Heuristics 9

  • Adobe Acrobat/Reader privileged API chain — CVE-2026-34621 critical CVE exact CVE_2026_34621
    PDF JavaScript matches the CVE-2026-34621 exploit chain: Acrobat internal UI/share APIs, swConn prototype/getter manipulation, and privileged RSS or file-read APIs used for staged command-and-control.
  • ClamAV: Pdf.Exploit.CVE_2026_34621-10060021-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.CVE_2026_34621-10060021-1
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • Optional Content Group with action trigger low PDF_OPTIONAL_CONTENT
    Optional Content Group (layer) co-occurs with an action trigger — content can be selectively hidden from viewers or scanners while the action still fires on open
  • AcroForm button with action trigger low PDF_ACROFORM_BUTTON
    PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
  • 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.
  • 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://'+webserver+'/'+mode0+a0_0x471eff(0x108)+Math
    • http://','invalid

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0011_000.js
ac4aa71c501d251717ff180f71d09f948b98863a4f321d6425e972c101ee65c0		 pdf-javascript-stream PDF /JS object 11 at offset 0x185FA 643 bytes
acroform_b64_00.js
30b37c04b7674373a869ca58f4e954426a1eb4b2dcc8e9bc96af01153e15d561		 deobfuscated-js PDF AcroForm base64 (raw) at offset 0x4AC 73936 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 7 eval/decoder/string-building token(s).

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