Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 1b5b296d23666b42…

MALICIOUS

RTF / .DOC

2.21 MB
MD5: 0d4881e7b37cf348025ff29b7c5e68c4 SHA-1: 9a74be8ce26251344f990e852ce1a782f73c7555 SHA-256: 1b5b296d23666b420cce79e0e953acc3ee864d7718ff7cfab7146ee85bb8b0f6
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The heuristics indicate the exploitation of this vulnerability, which is a common method for delivering malicious payloads. The embedded object is designed to activate and execute code, likely leading to the download and execution of a secondary stage.

Heuristics 5

  • 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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001116.bin
8eebabee892cfccb4afc0861dbf8da846e4aa7baa3a4f873ee224f3f316c1ec5		 rtf-objdata-decoded RTF \objdata at offset 0x1116 26862 bytes
objdata_01_off0001c6b1.bin
fe43efbadd674765243cb2580d9955cd54bcbea3b2eb0d6d648fe532cb7ef883		 rtf-objdata-decoded RTF \objdata at offset 0x1C6B1 476202 bytes

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