Update Date
01/18/2024

Class: IM-Worm

IM Worms spread via instant messaging systems (such as ICQ, MSN Messenger, AOL Instant Messenger, Yahoo Pager, Skype, etc.) In order to spread, IM-Worms usually send a link (URL) to a list of message contacts. The link leads to a network resource where a file containing the body of the worm has been placed. This tactic is almost exactly the same as that used by Email-Worms.

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Platform: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.

Family: Chydo

No family description

Examples

EACAD60A9B261B5A6F3BA8B4092B4253
066D485F0EAD03C69F7862A82F0A480E
DCE912C0E36350D5116BAD096EC977F0
7EB26AD16110DFF23F0EDCEC5D60DD20
00B5E32597053FFC72FFA333CF6CA0DB

Tactics and Techniques: Mitre*

TA0005
Defense Evasion

Adversaries may abuse the right-to-left override (RTLO or RLO) character (U+202E) to disguise a string and/or file name to make it appear benign. RTLO is a non-printing Unicode character that causes the text that follows it to be displayed in reverse. For example, a Windows screensaver executable named March 25 u202Excod.scr will display as March 25 rcs.docx. A JavaScript file named photo_high_reu202Egnp.js will be displayed as photo_high_resj.png.(Citation: Infosecinstitute RTLO Technique)


Adversaries may abuse the RTLO character as a means of tricking a user into executing what they think is a benign file type. A common use of this technique is with Spearphishing Attachment/Malicious File since it can trick both end users and defenders if they are not aware of how their tools display and render the RTLO character. Use of the RTLO character has been seen in many targeted intrusion attempts and criminal activity.(Citation: Trend Micro PLEAD RTLO)(Citation: Kaspersky RTLO Cyber Crime) RTLO can be used in the Windows Registry as well, where regedit.exe displays the reversed characters but the command line tool reg.exe does not by default.


T1036.002
Masquerading: Right-to-Left Override

Adversaries may abuse the right-to-left override (RTLO or RLO) character (U+202E) to disguise a string and/or file name to make it appear benign. RTLO is a non-printing Unicode character that causes the text that follows it to be displayed in reverse. For example, a Windows screensaver executable named March 25 u202Excod.scr will display as March 25 rcs.docx. A JavaScript file named photo_high_reu202Egnp.js will be displayed as photo_high_resj.png.(Citation: Infosecinstitute RTLO Technique)


Adversaries may abuse the RTLO character as a means of tricking a user into executing what they think is a benign file type. A common use of this technique is with Spearphishing Attachment/Malicious File since it can trick both end users and defenders if they are not aware of how their tools display and render the RTLO character. Use of the RTLO character has been seen in many targeted intrusion attempts and criminal activity.(Citation: Trend Micro PLEAD RTLO)(Citation: Kaspersky RTLO Cyber Crime) RTLO can be used in the Windows Registry as well, where regedit.exe displays the reversed characters but the command line tool reg.exe does not by default.


* © 2024 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

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