RTF / .DOC malware analysis — malicious · 828c15d94722cb54

MALICIOUS

RTF / .DOC

5.67 MB First seen: 2021-11-02

MD5: 6a189d7a893a37769edfb5b87b23743f SHA-1: f8ad8ce3c3d71d92e3b68f1c8fd9c19fd17cab69 SHA-256: 828c15d94722cb54496ea5305b792b2cdca80134121af96b0c65a2f5f72aaad2

222 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document containing OLE object data, specifically related to Microsoft Equation Editor. Critical heuristics indicate the presence of a CVE-2017-11882 exploit, which is known to facilitate the execution of arbitrary code. The excessive hex data and the decoded OLE object suggest that a malicious payload is embedded within the document, intended to be executed upon opening.

Heuristics 6

Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~5943KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000134c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x134C	2971648 bytes
SHA-256: `f9d7826b8b787436b9525f0e34b79bacc4404de95f4971d96e7d71948c658db5`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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