Malicious PDF — malware analysis report

Static analysis result for SHA-256 d21f77bf5c638e6a…

MALICIOUS

PDF

66.4 KB Created: 2021-02-19 04:37:56 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-07-10
MD5: 3ec4e391e786f810e36d128f0eb3cdee SHA-1: ac28b861cd14b822f33910bba77d233cfecd559f SHA-256: d21f77bf5c638e6a286626c871e75030a9f208f14e7b8fefa6b598f574996304
234 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF contains numerous links to external websites, including a known malicious redirector at 'https://yafferge.ru/wix?keyword=2013+writing+staar+test+answer+key'. The heuristic firings indicate a malformed exploit stream and a large number of SEO-linked PDFs, suggesting a phishing or malware distribution campaign. The ML classifier and ClamAV detection strongly support its malicious nature.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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.
  • 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.
  • 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://yafferge.ru/wix?keyword=2013+writing+staar+test+answer+key In PDF document text
    • https://cdn.sqhk.co/joduragenep/gfzsggw/49433783480.pdfIn PDF document text
    • https://cdn.sqhk.co/gasawivu/1aeaXhg/gif_to_video_converter_high_quality.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4453115/normal_600ed475bad57.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4403679/normal_5fdc1f4963960.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4368222/normal_602c105c6df9b.pdfIn PDF document text
    • https://cdn.sqhk.co/banijuwa/fih2haD/evolution_board_game_card_sleeves.pdfIn PDF document text
    • https://cdn.sqhk.co/jibenapola/4ib2Z7t/rock_out_loud.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4403130/normal_602f19e8a42a7.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4530937/normal_600bd6a677f6b.pdfIn PDF document text
    • https://vabemeraronoj.weebly.com/uploads/1/3/1/4/131452983/2024653.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://s3.amazonaws.com/tajimipojimo/kifugugemedatedizako.pdfIn PDF document text
    • https://s3.amazonaws.com/bejeseja/bruxelles_formation_call_center.pdfIn PDF document text
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000c64a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC64A 5476 bytes
SHA-256: ac84ab85785564957181de1825aab21953c5adc69b702749b6b6f57a339bddd4
font_01_sfnt_off0000d919.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD919 10392 bytes
SHA-256: 18473364180248216b7f5d0b1926d26485ce7fe8ddf0d22856588b4653d28294

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