Malicious PDF — malware analysis report

Static analysis result for SHA-256 91a5c22591fbeb69…

MALICIOUS

PDF

83.3 KB Created: 2021-04-16 12:10:15 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-08-20
MD5: 964b6357475f402188c4d60c6e923c7d SHA-1: b1ac3758850c4067771f765384035208cf539efd SHA-256: 91a5c22591fbeb69cf8ff76f6c95c6f5d0f3acdb64aa37bb21c81d43ec9d28cc
254 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

The PDF contains numerous links to external resources, many of which are SEO-optimized PDFs hosted on redirector domains. The primary redirector URL, 'https://yafferge.ru/strik?utm_term=english+language+grammar+lessons+pdf', suggests a lure to download educational materials, which is a common tactic for phishing or malware distribution. The ML classifier and ClamAV detection strongly indicate malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

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.
  • Image lure linking to an SEO redirector (free-download phishing) high PDF_SEO_UTM_REDIRECTOR_LINK
    PDF embeds an image with little or no body text and a clickable link to a multi-word utm_term / FeedBurner-proxied SEO redirector — the 'free ebook / solution-manual / document download' phishing family that ranks for natural-language search queries and routes the user into a payload/redirect chain. The PDF carries no exploit; the risk is the linked destination. Flagged structurally (image lure + SEO redirector) so it does not depend on a ClamAV/ML signature, and regardless of how many filler text pages the lure carries.
  • 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/strik?utm_term=english+language+grammar+lessons+pdf In PDF document text
    • https://cdn-cms.f-static.net/uploads/4421639/normal_603dba22bf4fd.pdfIn PDF document text
    • https://wumaviki.weebly.com/uploads/1/3/0/8/130874148/gatofi_pexaginotusasow_widebinulosu.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4483345/normal_604d21c23b618.pdfIn PDF document text
    • https://fevokixesebu.weebly.com/uploads/1/3/0/7/130776230/2c20e4.pdfIn PDF document text
    • https://banepopewux.weebly.com/uploads/1/3/4/2/134234854/f8ceac.pdfIn PDF document text
    • https://suveruwifofe.weebly.com/uploads/1/3/1/3/131380558/liboredofolepol.pdfIn PDF document text
    • https://nimaxosonoj.weebly.com/uploads/1/3/4/8/134897368/rusedikatupinara.pdfIn PDF document text
    • https://wovovude.weebly.com/uploads/1/3/1/3/131397940/9195408.pdfIn PDF document text
    • https://nifiguxo.weebly.com/uploads/1/3/1/3/131398563/e057bfc04d.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/mexesazaxasa/class_8_civics_chapter_3rd_question_answer.pdfIn PDF document text
    • https://02687da8-bf2b-436b-a8ca-82c6e04513a5.filesusr.com/ugd/e48f8a_4c708d87f6ec4bd29f3a4cefb204f6fe.pdf?index=trueIn PDF document text
    • https://s3.amazonaws.com/jevedijadiki/trigonometry_class_10_extra_questions_with_answers.pdfIn PDF document text
    • https://s3.amazonaws.com/wexukufedepim/format_flash_drive_bootable_windows_7.pdfIn PDF document text
    • https://s3.amazonaws.com/godoremitiwuja/getodapupifilorubomejuwu.pdfIn PDF document text
    • http://forubav.rf.gd/imovie_storyboard_template_printable.pdfIn PDF document text
    • https://dae57379-2785-4108-a223-4562ecbfc22e.filesusr.com/ugd/87ad98_a47c990302044cb89735df08f91eae9f.pdf?index=trueIn PDF document text
    • http://dejosabo.epizy.com/6186061642.pdfIn PDF document text
    • https://s3.amazonaws.com/kavifunaruvi/zofepus.pdfIn PDF document text
    • https://fb79ad55-22b5-4823-9538-35c71bbbd514.filesusr.com/ugd/ea423f_a9ba1a367ad345708b32c468363cae0e.pdf?index=trueIn PDF document text
    • https://8cff94d3-ecab-4ea5-ad27-d3e67d02fd32.filesusr.com/ugd/2813e2_09e6372e2aa3455ca0b13d19470d0d55.pdf?index=trueIn PDF document text
    • https://80b1f93a-fe74-4439-a81d-34814fa7a505.filesusr.com/ugd/e56fe2_78b17c3b4b9f4364ad1d6a4a0469830a.pdf?index=trueIn 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_off00010561.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10561 5412 bytes
SHA-256: bba72aa399a1565cec48b1a66df4dda4254e87f468e0c091dfcf79be62bcfa2f
font_01_sfnt_off000117a2.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x117A2 12400 bytes
SHA-256: 7425a63c3982d0a8dc69c4cf688cf4cbab1776fdcda415afa12456fdbcc6e715