PDF malware analysis — malicious · d7c2f7041f88a370

MALICIOUS

PDF

8.2 KB

MD5: 1c939b487b5faa20c680578394c9d00f SHA-1: b853fa05b70967c77f3a94b2ea5155486fa38b13 SHA-256: d7c2f7041f88a3703aa70be186b6dbd5f91dd9aceae348f9be3dbdb141a40332

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.001 Malicious Link T1071.001 Web Protocols T1566.001 Spearphishing Attachment T1566.002 Spearphishing Link

The PDF file contains obfuscated JavaScript, identified as a dropper, which leverages the CVE-2007-5659 vulnerability. This vulnerability is exploited through the `Collab.collectEmailInfo` function, which reads an encoded payload from an annotation subject. The script then decodes this payload and likely executes it, serving as a multi-stage downloader. The presence of anti-analysis checks like `app.plugIns.length` further indicates malicious intent. The extracted JavaScript streams and the specific heuristic firings strongly suggest a dropper mechanism designed to fetch and execute further malicious content.

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` `b97943fdac850fd496295d5b5cf934affecf8a3e4b1c1b8969b6004765b8478e`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B68	1832 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` `7d21aa7a60d38c2d107ad392d0df7cef994e9a30dcccc732f3ab2d5eefaa7a56`	deobfuscated-js	annotation-subject callee-key decoded JavaScript at offset 0x359	5104 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).
`deobfuscated.js` `7099db53b5574029b1cda6f0a5600c92dceb6ec4852feccee354db72b985302d`	deobfuscated-js	PDF JavaScript deobfuscation pass	20043 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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