RTF / .DOC malware analysis — malicious · 17c76fbc1649cb50

MALICIOUS

RTF / .DOC

2.50 MB First seen: 2022-07-28

MD5: 03997f12d6b1af4477a58c19b61bc077 SHA-1: 07d35807617d89534fd2f2dfa893b85caa10279f SHA-256: 17c76fbc1649cb502496d4ab062d6847466bbb2cb5eec24d96b10fc9f976c1fc

442 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File T1559.001 Component Object Model Hijacking T1204 User Execution

The RTF document contains embedded OLE objects and exploits known vulnerabilities, specifically CVE-2017-11882 and CVE-2018-0798, to activate and execute a payload. ClamAV detections indicate the embedded artifact is a Remote Access Trojan (AsyncRAT). The excessive hex data and PE header within the OLE object further confirm the presence of a malicious executable.

Heuristics 11

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.
CVE-2018-0798 — suspicious MTEF Matrix record high CVE likely CVE_2018_0798

RTF contains Equation Editor data with an anomalous MTEF Matrix record (oversized dimension byte + repeated padding). This may be a variant of CVE-2018-0798 (Matrix record stack overflow in EQNEDT32.EXE).
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 ~1893KB 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_off000012ab.bin` `a845832d512d42730c7e72161576f28a8e0faed77a2e6998cfb71142809eee57`	rtf-objdata-decoded	RTF \objdata at offset 0x12AB	952645 bytes
Detection ClamAV: Win.Trojan.AsyncRAT-9914220-0 Obfuscation or payload: likely Carved artifact entropy is 7.70, consistent with packed or encrypted content.
`objdata_01_off001d86c0.bin` `be008ac939deab73a9c9495546d8254146b2be045989f91ea9153bd4e8489f59`	rtf-objdata-decoded	RTF \objdata at offset 0x1D86C0	140002 bytes

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