Malicious RTF — malware analysis report

Static analysis result for SHA-256 4bc611d580618f0d…

MALICIOUS

RTF

2.83 MB First seen: 2022-08-16
MD5: 4c22302abe0b2b84c63a69ce2c071883 SHA-1: aa2cf936ee452332d0ae06e05a6a7e456ead2aa0 SHA-256: 4bc611d580618f0d2fefb8d1825a3bc6cbaa7d49a766fd2acd528247c6ad7a5f
382 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File Execution T1559 Component Object Model Hijacking T1059.001 PowerShell

The RTF document contains multiple indicators of exploitation, including OLE object data, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics. The presence of a PE header within the hex-encoded OLE object data strongly suggests that a malicious executable payload is embedded. ClamAV detection as Rtf.Dropper.Agent-9965975-1 further confirms its malicious nature as a dropper.

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.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • 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
  • \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 ~2010KB 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.

FilenameKindSourceSize
objdata_00_off0000129e.bin
a23eef13c91b3f0dcc798cd950c25ef0a05b5da19a5fc85011f0c6fbedbb30a1
rtf-objdata-decoded RTF \objdata at offset 0x129E 1011013 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.
objdata_01_off001f4ea6.bin
a2124a25b651c0ac4f1b03472e0b5f0f351a1ff2bdd6230b727bd3863ad79f3d
rtf-objdata-decoded RTF \objdata at offset 0x1F4EA6 187261 bytes