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Reversing Multilayer .NET Malware

This post was authored by Dave McDaniel with contributions from Jaeson Schultz

Recently, we came across a malware sample that has been traversing the Internet disguised as an image of a woman. The malware sample uses several layers of obfuscation to hide its payload, including the use of steganography. Steganography is the practice of concealing a message, image, or file within another message, image, or file. Steganography can be used in situations where encryption might bring unwanted attention. Encrypted traffic from an unusual source is going to draw unwanted attention. Steganography allows malicious payloads to hide in plain sight. It also allows the attacker to bypass security devices. In our sample malware, steganography is used to decrypt and execute a second dropper, which in turn installs a user-land rootkit to further hide its intentions. The rootkit adds another layer of obfuscation by installing a DarkComet backdoor, using RC4 encryption to encrypt its configuration settings and send data to its command and control server.

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Microsoft Update Tuesday November 2014: Fixes for 3 0-day Vulnerabilities

This month Microsoft is releasing 14 security bulletins. Originally they had planned to release 16, but due to issues that emerged in late testing, two bulletins that were announced in the Advance Security Notification, MS14-068 and MS14-075, have been postponed. Of the 14 bulletins, four are considered critical, eight are important, while two are moderate. They cover a total of 33 CVEs.

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Talos Discovered Three More Vulnerabilities in Pidgin

This post was authored by Yves Younan and edited by Armin Pelkmann

Table of contents

CVE-2014-3697, VRT-2014-0205
CVE-2014-3696, VRT-2014-0204
CVE-2014-3695, VRT-2014-0203

Cisco Talos is announcing the discovery and patching of another three 3 CVE vulnerabilities in Pidgin (An open-source multi-platform instant messaging client -- see wikipedia page). These vulnerabilities were discovered by our team and reported to the Pidgin team. They were found during our initial look at Pidgin which resulted in the first 4 vulnerabilities released in January, but were reported to Pidgin a little later and took longer to get patched. Now that these vulnerabilities were patched in the latest version of Pidgin, 2.10.10, we want to publicly disclose our findings.

 

The first vulnerability (CVE-2014-3697, VRT-2014-0205) is in the routines Pidgin uses to handle smiley and theme packages in Windows. These packages can be downloaded from websites and installed by dragging and dropping them to Pidgin. The packages are TAR files and Pidgin handles them by un-tarring the files to a specific directory. Read More »

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Threat Spotlight: Group 72, Opening the ZxShell

This post was authored by Andrea Allievi, Douglas Goddard, Shaun Hurley, and Alain Zidouemba.

Recently, there was a blog post on the takedown of a botnet used by threat actor group known as Group 72 and their involvement in Operation SMN.  This group is sophisticated, well funded, and exclusively targets high profile organizations with high value intellectual property in the manufacturing, industrial, aerospace, defense, and media sector. The primary attack vectors are watering-hole, spear phishing, and other web-based attacks.

Frequently, a remote administration tool (RAT) is used to maintain persistence within a victim’s organization. These tools are used to further compromise the organization by attacking other hosts inside the targets network.

ZxShell (aka Sensocode) is a Remote Administration Tool (RAT) used by Group 72 to conduct cyber-espionage operations. Once the RAT is installed on the host it will be used to administer the client, exfiltrate data, or leverage the client as a pivot to attack an organization’s internal infrastructure.  Here is a short list of the types of tools included with ZxShell:

  • Keylogger (used to capture passwords and other interesting data)
  • Command line shell for remote administration
  • Remote desktop
  • Various network attack tools used to fingerprint and compromise other hosts on the network
  • Local user account creation tools

For a complete list of tools please see the MainConnectionIo section.

The following paper is a technical analysis on the functionality of ZxShell. The analysts involved were able to identify command and control (C2) servers, dropper and installation methods, means of persistence, and identify the attack tools that are core to the RAT’s purpose. In addition, the researchers used their analysis to provide detection coverage for Snort, Fireamp, and ClamAV.

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Weaponized Powerpoint in the Wild

This post was written by Jaeson Schultz.

On October 14th information related to a new Windows vulnerability, CVE-2014-4114, was published. This new vulnerability affects all supported versions of Microsoft Windows. Windows XP, however, is not affected by this vulnerability. The problem lies in Windows’ OLE package manager. When triggered it allows for remote code execution.

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