Malicious PDF — malware analysis report

Static analysis result for SHA-256 991f633f0f79606e…

MALICIOUS

PDF

74.8 KB Created: 2021-03-04 02:45:01 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-20
MD5: 45d92aea755185ef3812f33fb716f87e SHA-1: 213c9606e5e9a4973875e0ed64396e7b664d17fe SHA-256: 991f633f0f79606e5efd5f9e523974b1aa10a1adeef403b37d916ab224e06597
264 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF contains a large number of embedded links pointing to external PDF files hosted on various domains, many of which appear to be disposable. One critical heuristic identified a link to known malicious redirector infrastructure. The ML classifier also strongly flagged this PDF as malicious. The document body is heavily obfuscated and appears to contain metadata rather than user-facing content, suggesting its primary purpose is not informational but rather to facilitate the distribution of other malicious or SEO-manipulating content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 7

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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.
  • 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.
  • Callback phishing phone lure medium SE_CALLBACK_LURE
    Document asks the user to call a phone number in billing, refund, subscription, fraud, or security context — consistent with callback phishing or tech-support scam patterns. Suppressed for legitimate-issuer (IRS/gov/official-form) documents that carry no urgency or charge/dispute escalation.
  • 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://crophysi.ru/strik?utm_term=the+red+tent+book+summary In PDF document text
    • https://static.s123-cdn-static.com/uploads/4374536/normal_5ffc0835da10a.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4373788/normal_5fc7a59c19e4c.pdfIn PDF document text
    • https://japipimimobuxi.weebly.com/uploads/1/3/1/0/131071183/5bba0506c46.pdfIn PDF document text
    • https://sudewivozuv.weebly.com/uploads/1/3/2/3/132303071/7a5dae.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4479917/normal_5fd2e0f222191.pdfIn PDF document text
    • https://furimubabo.weebly.com/uploads/1/3/1/8/131856330/gewesomot_lepevadiluzapiv.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4380695/normal_600a4956e1c43.pdfIn PDF document text
    • https://fovejurifeke.weebly.com/uploads/1/3/4/3/134342496/3763351.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4373504/normal_5fee52835ca4f.pdfIn PDF document text
    • https://zimovezinidukiv.weebly.com/uploads/1/3/1/4/131453924/mavipuvi.pdfIn PDF document text
    • http://kutakelipaxeb.22web.org/crib_sheets_size.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4392861/normal_6012982bc8e41.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4375704/normal_602dc9ad0214f.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4387704/normal_5ff7b2419f5ed.pdfIn PDF document text
    • https://luxituwane.weebly.com/uploads/1/3/1/8/131859527/sexowumaxow.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4485005/normal_603479846017a.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4474977/normal_60402c2d102c2.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4425921/normal_5feb2218e5d83.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn 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_off0000e89d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE89D 5288 bytes
SHA-256: d5f900a54beb2a93be0889e7b39e56191f0dfb1944ad45b2e1e08eb8e8e1b111
font_01_sfnt_off0000fa6f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFA6F 10544 bytes
SHA-256: da49ab719c88d681874bc6aa116ce6759cfb35ac15830d210f894b09166fd949