Malicious PDF — malware analysis report

Static analysis result for SHA-256 26cc8e01291cc6f9…

MALICIOUS

PDF

11.5 KB
MD5: 27c8bcb2eeb10ff249a9b99fe9f8ae85 SHA-1: 42754a14c713d7a8839222cf3ffb7b03039b2859 SHA-256: 26cc8e01291cc6f9adf336b5b69f316f8563dac10d9d76d290bede2675d792ad
126 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1204.002 Malicious Link/URL

The critical heuristic firing for CVE_2007_5659 indicates the exploitation of a known vulnerability in PDF documents using the 'collab.collectEmailInfo' JavaScript function. The PDF launcher uses a callee.toString()-keyed hex decoder to obfuscate a JavaScript stager, which is then evaluated. This stager is responsible for downloading and executing a second-stage payload, though the exact URL is not recoverable from the provided evidence. The presence of multiple JavaScript-related heuristics and the specific exploit firing strongly suggest this attack pattern.

Heuristics 6

  • Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659
    PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
  • Annotation subject callee-key hex JavaScript stager high PDF_ANNOT_SUBJECT_CALLEE_HEX_STAGER
    PDF JavaScript uses syncAnnotScan()/getAnnots() to read an indirect annotation /Subject stream, percent-decodes it through marker replacement, then uses a callee.toString()-derived key to decode and eval the final exploit stage.
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0007_000.js
c860bd3a1b8438b37e98a599719a1868ae540624631f091272ffef48912644f4
pdf-javascript-stream PDF /JS object 7 at offset 0x19C 579 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
annotation_subject_callee_hex_stage_000.js
21197c91aa795ee9aa3fbda1f6456d6fb35dd4b0fc13df0b2e48afc8de7aea6f
deobfuscated-js annotation-subject callee-key decoded JavaScript at offset 0x14A 5036 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).