PDF malware analysis — malicious · ae961bf7f7dab1da

MALICIOUS

PDF

7.9 KB

MD5: b6ccac40f07772134bcaf0ee05bd35f3 SHA-1: 4d9d0fd29c50a5c994ce4d039978184da9f2bc14 SHA-256: ae961bf7f7dab1da07a0848f7c7e0fabce9a39a2ba6b5eba3ebeb1680bf04ead

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link

The PDF file contains obfuscated JavaScript, identified as a multi-stage dropper. It leverages the CVE-2007-5659 vulnerability, specifically using the `Collab.collectEmailInfo` method to execute the embedded JavaScript. The script's primary function appears to be downloading and executing a second-stage payload, indicated by the 'Obfuscated multi-stage PDF JavaScript dropper' heuristic. The presence of `String.fromCharCode` and hex-encoded payloads further supports this analysis.

Heuristics 7

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)
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, hex_dashed_payload, 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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `9d5c7e01faed5b04e9ec11f1d98b73f0012c871beaf60e9f9d32ad6df00d46f7`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	550 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` `fe2a54b79e449e1074a1b152960d2221753cb5fbca8f5a5c8e45c4e2e18a9a7c`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1A5B	1800 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` `22e2c7914f8fb113fc989e82c6e0db2c2d49a9dbc0e5eccc765f5c36b5692e66`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x359	4811 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `674f33ae97ac1b00165f92536b518db647a3fc1e941b606d44730a168af0a86d`	deobfuscated-js	PDF JavaScript deobfuscation pass	23211 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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