Malicious PDF — malware analysis report

Static analysis result for SHA-256 a29ce95f104e5f6d…

MALICIOUS

PDF

17.1 KB
MD5: 2c05d569a6af2698d0882f14bf8ddc1a SHA-1: 2cab4541ecb8669f8deac0a80529edfc1d151d5d SHA-256: a29ce95f104e5f6dbdc492b4900ba8620d99ea3b1aff840cf5a74125a028cf92
234 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript T1204.001 Malicious Link T1071.001 Web Protocols

The PDF contains a critical heuristic firing for CVE-2007-5659, indicating the exploitation of a vulnerability related to the `Collab.collectEmailInfo` function. This is further supported by high-confidence heuristics for an obfuscated multi-stage JavaScript dropper that uses annotation subjects as encoded payloads. The JavaScript is decoded using a hex codec and incrementally evaluated, a common technique for downloading and executing further stages. No document body text was available for analysis, but the heuristics strongly suggest a malicious exploit delivery mechanism.

Heuristics 9

  • 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
  • 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.
  • 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.

FilenameKindSourceSize
javascript_obj0009_000.js
4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d
pdf-javascript-stream PDF /JS object 9 at offset 0x41DA 469 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
b194474218787595d8c267324a0a5fa5b542803851cb5f0b633d666dba136e75
deobfuscated-js annotation-subject callee-key decoded JavaScript at offset 0x1A24 5221 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
deobfuscated.js
6787a7e67e30d34d86389a0e17ba064232cf5c4a8743af8443edf2a00f08752d
deobfuscated-js PDF JavaScript deobfuscation pass 94507 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 6 eval/decoder/string-building token(s). Carved artifact contains 3 long base64-like blob(s).