PDF malware analysis — malicious · 9b9cef3e5d0f9a7a

MALICIOUS

PDF

17.7 KB

MD5: 3d176a6be5dd6031fa7ec9e08ca2056f SHA-1: c522d0e058e035dc9668705fd3e1aaddfe63da29 SHA-256: 9b9cef3e5d0f9a7a8ed2f7f53e0d1cdc10c7179ca24c77459d929b6204a3f645

194 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript T1204.001 Malicious Link or Macro: Malicious Link T1071.001 Web Protocols: HTTP

The PDF file contains obfuscated JavaScript, identified as a multi-stage dropper. Static analysis indicates it leverages the CVE-2007-5659 vulnerability (Collab.collectEmailInfo) to execute this script. The script is designed to download and execute a second-stage payload, as evidenced by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic and the presence of large deobfuscated JavaScript artifacts. The primary attack vector appears to be exploiting a known PDF vulnerability to facilitate further malicious activity.

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-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 4 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, 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.
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)
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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0009_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 9 at offset 0x4450	469 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` `47b1c620c5ebd2a61f651fc54fb82a65c22714e4762dede1935cc34689b60c3a`	deobfuscated-js	z-percent UTF-16BE base-21 decoded JavaScript at offset 0x1B20	5348 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `c07b3605c49eac059d0ded16646a1c012f4a4abb7d5a38b1a3320860baebde62`	deobfuscated-js	PDF JavaScript deobfuscation pass	174735 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).

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