Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 6347d4b4f6fa3c2e…

MALICIOUS

RTF / .DOC

27.7 KB First seen: 2022-11-22
MD5: 6be52a2a954727135b1e046e14bcc601 SHA-1: a37a0799d2cdff1e0dc0250617503e698d42faa1 SHA-256: 6347d4b4f6fa3c2e2e69179c9a92a362f90fbd58e56635ff09b1976bd4b6000d
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 User Execution: Malicious File T1059.005 PowerShell

The sample is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body contains a lure instructing the user to 'Enable editing', a common tactic to bypass macro security. The exploit is designed to execute arbitrary code, likely to download and run a second-stage payload.

Heuristics 6

  • 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.
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00005609.bin
61b65244d5f00a3b7dc458cc5c2f6c4be7a3d462311fe6774ddcd71333bd268d		 rtf-objdata-decoded RTF \objdata at offset 0x5609 1395 bytes

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