Malicious PDF — malware analysis report

Static analysis result for SHA-256 dffd97b91cd79901…

MALICIOUS

PDF

68.2 KB Created: 2020-12-18 20:28:32 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 343822293a87f72a314f0c5b77ce030d SHA-1: d7041556b9c4cb15ddb7d518342ed8934bb84139 SHA-256: dffd97b91cd79901daacb6e07804282b1f6f2ca30f21a433f973903d9a64ce1a
244 Risk Score

Malware Insights

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

The PDF contains a large number of embedded links, many pointing to disposable hosting, indicative of a link farm. One critical heuristic identified a link to known malicious redirector infrastructure. ClamAV also detected this file as a phishing trojan. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool often used to create PDFs from web content, further supporting the link farm hypothesis.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • 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.
  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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 https://traffmen.ru/strik?utm_term=virtual+lab+5+types+of+chemical+reactions+worksheet+answers
    • https://cdn-cms.f-static.net/uploads/4457570/normal_5fbb170431056.pdf
    • https://vakenufepuxino.weebly.com/uploads/1/3/4/5/134529081/90ed3be38e4e.pdf
    • https://jiraxoxaxizare.weebly.com/uploads/1/3/4/0/134012395/wuwubonakopuvutoxosa.pdf
    • https://sulidisige.weebly.com/uploads/1/3/4/3/134318683/c57772ac73b.pdf
    • https://menuvudojowakap.weebly.com/uploads/1/3/4/5/134594867/992225a.pdf
    • https://tisemadu.weebly.com/uploads/1/3/4/3/134387657/7359880.pdf
    • https://jalewigevat.weebly.com/uploads/1/3/2/6/132681207/sokufejopum_tugavetinetumis_loragufil.pdf
    • https://lafozevu.weebly.com/uploads/1/3/4/3/134378288/b704508e.pdf
    • https://xufidevudog.weebly.com/uploads/1/3/4/3/134389214/bexefimofoma.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/3e0f9e3b-c4a7-4187-a6a0-961c722777b5/phycology_book.pdf
    • https://s3.amazonaws.com/kujesulad/8778437216.pdf
    • https://uploads.strikinglycdn.com/files/d9120184-bc88-46ff-aee1-f912d83e983c/fatim.pdf
    • https://s3.amazonaws.com/sukobogixe/codehs_snowman_answers.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000ca7f.bin
4b42d9615915baf103f6c5cb517699332a3c9e59accff7b39ebaddf32372427a
pdf-font-stream PDF embedded font (sfnt) at offset 0xCA7F 5744 bytes
font_01_sfnt_off0000ddfc.bin
9a276bd4f1916703f5b74316b5d5660d5e85b7b088850e1af98f6afee54fb83e
pdf-font-stream PDF embedded font (sfnt) at offset 0xDDFC 11036 bytes