RTF malware analysis — malicious · 72eaa7f57c3f6201

MALICIOUS

RTF

3.76 MB First seen: 2022-07-20

MD5: 6b06fad6e80f32acc96772f0abb8b489 SHA-1: 30861381bebb5da60eade98bddcf40f4b2e06393 SHA-256: 72eaa7f57c3f6201cc37812d03ddd0d1c6fc4a71c913242c8cc52b1dc9e11ade

402 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The RTF file contains multiple indicators of malicious activity, including OLE object data and specific heuristics pointing to the CVE-2017-11882 Equation Editor exploit. ClamAV detections confirm this, identifying the file as a dropper and an extracted artifact as AsyncRAT. The embedded OLE object likely contains a PE executable, which is then executed on the victim's machine.

Heuristics 10

Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED

RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger 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.
PE header (with DOS stub) in hex data critical RTF_MZ_HEX

Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
\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 ~1901KB 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
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00001284.bin` `e746be256226225fb4c022cadac54afebddb2f746cd0dae87ba5900a29b18e2f`	rtf-objdata-decoded	RTF \objdata at offset 0x1284	968491 bytes
Detection ClamAV: Win.Trojan.AsyncRAT-9914220-0 Obfuscation or payload: likely Carved artifact entropy is 7.88, consistent with packed or encrypted content.
`objdata_01_off001e5a22.bin` `ee689f3f3e104d316fdfdcc5da12c6430bbbcc7bd0a9e503676477f2b53390b6`	rtf-objdata-decoded	RTF \objdata at offset 0x1E5A22	462748 bytes

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