RTF / .DOC malware analysis — malicious · 1878d067011a763e

MALICIOUS

RTF / .DOC

2.01 MB First seen: 2022-04-22

MD5: 415485bbad16a886944cc164c39ee1b8 SHA-1: c5c295b841513dd477c097c7da22b377a4b4d29a SHA-256: 1878d067011a763e3fdf15143b9c407dca327ee1592830f0fed9b1f8d24bd7f5

222 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object related to CVE-2017-11882, indicating exploitation of the Equation Editor vulnerability. The high entropy and large size of the decoded OLE object suggest it hides a second-stage payload. The presence of ".objdata" and ".objupdate" directives further support the malicious intent of activating embedded objects.

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 ~2106KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 1 \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_off0000003d.bin` `7a5d8b3f1b19830e395b14d0068038f8ec307ccc995c29b7c0171c59f5840ca9`	rtf-objdata-decoded	RTF \objdata at offset 0x3D	1053122 bytes
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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