Malicious PDF — malware analysis report

Static analysis result for SHA-256 c9ccee3f320c8a8e…

MALICIOUS

PDF

28.9 KB Created: 2021-07-04 20:17:37 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-11-22
MD5: e5b56171cf4e2e6a22f41835d1ca8f65 SHA-1: b9c782fdeafa72fa46ed710abc8308e86740b0b2 SHA-256: c9ccee3f320c8a8eb7a3acb4de948506a0e1a286788c1b1874c2eb020065a98e
150 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains a malformed exploit stream and a critical heuristic firing indicates a link to known malicious redirector infrastructure. The document body and embedded URL point to a lure for 'free Robux', a common social engineering tactic. The embedded URL is `http://netcdn.tw/app/431946152/free-robux-no-verification-or-survey-2021-game-hack`, which is likely used to download and execute a second-stage payload.

Machine Learning

  • Nyx PDF Classifier clean score 0.0632

Heuristics 5

  • PDF links to a 'free generator / game hack' redirector critical PDF_GAME_HACK_REDIRECT_LURE
    PDF's clickable action targets a redirector of the form /app/<id>/<slug>-game-hack — the landing-page shape of a large SEO 'free spins / generator / game hack' lure family that funnels victims through rotating disposable hosts to a malware/scam payload. The multi-link variants also trip ML/link-farm rules; this catches the single-link variants that otherwise score clean. CRITICAL on its own: the /app/<id>/<slug>-game-hack path shape is unambiguous scam infra, and the host rotates so a host-list match can't be relied on.
  • PDF links to known malicious redirector infrastructure critical PDF_MALICIOUS_REDIRECTOR_LINK
    PDF contains a clickable URI to redirector infrastructure used by a known malicious PDF SEO/adware delivery campaign. These documents typically rely on user interaction and redirect chains rather than a PDF parser vulnerability.
  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • 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://netcdn.tw/app/431946152/free-robux-no-verification-or-survey-2021-game-hack In PDF document text
    • http://en.wikipedia.org/wiki/MIT_LicenseIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000178c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x178C 22880 bytes
SHA-256: 53b65e469753881fc89f3b9fe2b387d554a23c82fedecc6015634dbab5ba0be2
font_01_sfnt_off00004adb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x4ADB 19772 bytes
SHA-256: a441bd845f25f30d9b35deb0a49928c69a030f2d5bccbb8c502819d18c42e29e

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