Malicious PDF — malware analysis report

Static analysis result for SHA-256 e8aaf76746279e67…

MALICIOUS

PDF

7.7 KB
MD5: b9cbeba77e0ea39908780c101087868a SHA-1: 8e8003b669a7b16de538e0aa87e00b5ddbea7d73 SHA-256: e8aaf76746279e67e3fba5e8dfe52cdfa6c18a18c3bb379b13a1e71d5a0b7976
256 Risk Score

Malware Insights

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

The PDF document contains obfuscated JavaScript, identified as a multi-stage dropper. This script leverages the CVE-2007-5659 vulnerability, specifically using the Collab.collectEmailInfo method to decode and execute a payload. The presence of multiple deobfuscated JavaScript files and high ML classifier scores indicate a malicious intent to download and execute further stages of malware. The primary attack vector is the exploitation of a known PDF vulnerability.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 8

  • 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)
  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, incremental_eval_build, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
  • 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.
  • syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN
    PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
f9b4659beaf681d266cfb5046d495e7b144d406eff72e71ecd4d1451ae25ca11
pdf-javascript-stream PDF /JS object 6 at offset 0x143 481 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
bbdb1413ed8572626ca180fad41c50fc02e65d46b00bd25a6f6cad0c14323706
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x19F4 1673 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_001.js
9ba6dc7fa8bbbfabb6ce2a72bde80ea091ed611d4b7985dae2cd888a80f96b1a
deobfuscated-js annotation-subject callee-key decoded JavaScript at offset 0x329 4976 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
deobfuscated.js
75706dfa1418429cc60099fa619ad558d484213607ac13b2482b0b1cd3256de2
deobfuscated-js PDF JavaScript deobfuscation pass 24792 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).