9.3 - TA10-055A

Malicious activity detected in mid-December targeted at least 20
organizations representing multiple industries including chemical, finance, information technology, and media. Investigation into this activity revealed that third parties routinely accessed the personal email accounts of dozens of users based in the United States, China, and Europe. Further analysis revealed these users were victims of previous phishing scams through which threat actors successfully gained access to their email accounts.

I. Description

Through analysis of the malware used in this incident, McAfee discovered one of the malware samples exploited a vulnerability in Microsoft Internet Explorer (IE). The vulnerability exists as an invalid pointer reference within IE and, if successfully exploited, allows for remote code execution.

Microsoft has released Security Bulletin MS10-002, which provides updates for Internet Explorer that address this and other vulnerabilities.

US-CERT is providing technical indicators that can be incorporated into an organizations security posture to detect and mitigate any malicious activity.

Please see
for further detail.

The following signatures can be deployed to assist in detecting
malicious activity associated with this incident:

Primary Malware Beacon

alert tcp any any -> any any (msg:"Targeted Malware Communication Beacon Detected"; flow:to_server,established; dsize:20;
content:"|ff ff ff ff ff ff 00 00 fe ff ff ff ff ff ff ff ff ff 88
ff|"; depth:20; sid:7777777; rev:1;)

Secondary Malware Beacon

alert tcp any any <> any any (msg:"ORC:DIS:BEACON_380DFF";
content:"|38 0d ff 0a d7 ee 9d d7 ec 59 13 56|"; sid:99980060;
rev:1;)

Note: US-CERT has not verified or tested these signatures and recommends proper testing prior to deployment.

II. Impact

By convincing a user to view a specially crafted HTML document or Microsoft Office document, an attacker may be able to execute arbitrary code with the privileges of the user.

III. Solution

The Internet Explorer vulnerability used in these attacks is addressed with the updates provided in Microsoft Security Bulletin MS10-002.

Other recommendations include:

* As a best practice, limit end-user permissions on systems by granting minimal administrative rights.
* Enable Data Execution Prevention (DEP) for IE 6 Service Pack 2 or IE 7. IE 8 automatically enables DEP.
* Inspect network traffic history for communication with external systems associated with the attack.
* Examine computers for specific files or file attributes related to the attack.