Friday, January 18, 2019

Threat Roundup for Jan. 11 to Jan. 18

Today, Talos is publishing a glimpse into the most prevalent threats we've observed between Jan. 11 and Jan. 18. As with previous roundups, this post isn't meant to be an in-depth analysis. Instead, this post will summarize the threats we've observed by highlighting key behavioral characteristics, indicators of compromise, and discussing how our customers are automatically protected from these threats.

As a reminder, the information provided for the following threats in this post is non-exhaustive and current as of the date of publication. Additionally, please keep in mind that IOC searching is only one part of threat hunting. Spotting a single IOC does not necessarily indicate maliciousness. Detection and coverage for the following threats is subject to updates, pending additional threat or vulnerability analysis. For the most current information, please refer to your Firepower Management Center,, or

Thursday, January 17, 2019

What we learned by unpacking a recent wave of Imminent RAT infections using AMP

This blog post was authored by Chris Marczewski

Cisco Talos has been tracking a series of Imminent RAT infections for the past two months following reported data from Cisco Advanced Malware Protection's (AMP) Exploit Prevention engine. AMP successfully stopped the malware before it was able to infect the host, but an initial analysis showed a strong indication that stages exist before the deployment of the RAT. Surprisingly, the recovered samples showed no sign of Imminent RAT, but instead a commercial grade packer.

This was a series of attacks engineered to evade detection and frustrate analysis. From the outside, we have a commercially available, yet affordable packer called "Obsidium" that has been used in the past to protect the intellectual property of some legitimate software vendors. The payload results in a RAT called Imminent that has also been used previously for legitimate purposes. Imminent is a commercially available RAT that retails for $25 to $100, depending upon the size of the customer's expected user base. While it is not intended for malicious use, in this case, its detection suggested otherwise.

Although a Potentially Unwanted Application (PUA) detection approach could suffice, not everyone enables blocking of PUAs. We have other technologies in place, such as the Exploit Prevention engine, that are well-suited to detect such threats. We hope that after reading this research, you'll have a better understanding of not only what it takes to investigate an attack using a complex packer, but also how AMP is equipped to stop such attacks that planned on successfully evading static detection or thwarting the benefits of dynamic analysis from a malware sandbox.

Cisco Talos' new reputation dispute system

We know users have been waiting for this feature for a while, and we are here to say: It’s ready.  Cisco Talos’ new reputation system rolled out Jan. 14 on We have been working on this change since the rollout was initially announced this past summer.

Beers with Talos EP44: Fun with 2018’s Worst and Talks We Want to Hear

Beers with Talos (BWT) Podcast Ep. #44 is now available. Download this episode and subscribe to Beers with Talos:

If iTunes and Google Play aren't your thing, click here.

Ep. #44 show notes: 

Recorded Jan. 7, 2018

Most of the episode (after an extended roundtable — we all had a lot to get out after time off), we look back at the 2018 Malware Year in Review, including Olympic Destroyer, VPNFilter, MDM and other unique, large-scale, or otherwise interesting bits of malware that Talos encountered. We also discuss the things we would love to see conference talks about in the new year. Of course, we use that to announce the CFP for Talos Threat Research Summit 2019. If you do defense and want to talk to other defenders, make sure to submit before Jan. 25 here.

Wednesday, January 16, 2019

Dynamic Data Resolver (DDR) - IDA Plugin

This blog post was authored by Holger Unterbrink

Executive Summary

Static reverse-engineering in IDA can often be problematic. Certain values are calculated at run time, which makes it difficult to understand what a certain basic block is doing. But, if you try to perform dynamic analysis by debugging a piece of malware, the malware will often detect it and start behaving differently. Cisco Talos is here with Dynamic Data Resolver (DDR) a new plugin for IDA that aims to make the reverse-engineering of malware easier.

Tuesday, January 15, 2019

Emotet re-emerges after the holidays

While Emotet has been around for many years and is one of the most well-known pieces of malware in the wild, that doesn't mean attackers don't try to freshen it up. Cisco Talos recently discovered several new campaigns distributing the infamous banking trojan via email. These new campaigns have been observed following a period of relatively low Emotet distribution activity, corresponding with the observance of Orthodox Christmas in certain geographic regions. These new malicious efforts involve sending victims malicious Microsoft Word attachments with embedded macros that download Emotet.

This latest strain has also gained the ability to check if the infected IP where the malicious email is being sent from is already blacklisted on a spam list. This could allow attackers to deliver more emails to users' inboxes without any pushback from spam filters.

Vulnerability Deep Dive: TP-Link TL-R600VPN remote code execution vulnerabilities

Vulnerability discovery and research by Jared Rittle and Carl Hurd of Cisco Talos.


TP-Link recently patched three vulnerabilities in their TL-R600VPN gigabit broadband VPN router, firmware version 1.3.0. Cisco Talos publicly disclosed these issues after working with TP-Link to ensure that a patch was available. Now that a fix is out there, we want to take the time to dive into the inner workings of these vulnerabilities and show the approach we took with our proof-of-concept code.


The TP-Link TL-R600VPN is a five-port small office/home office (SOHO) router. This device contains a Realtek RTL8198 integrated system on a chip. This particular chip uses an offshoot of the MIPS-1 architecture developed by Lexra. Except for a few proprietary instructions for handling unaligned load and store operations, these two instruction sets are essentially the same. The instructions that are not included in Lexra are LWL, SWL, LWR, and SWR. These proprietary instructions are often used when compiling a program for the more common MIPS-1 architecture and cause a segfault when encountered in Lexra. The knowledge of this key difference is imperative to assembling working code for the target.

For more information about Lexra MIPS and its differences with the MIPS-1 architecture, refer to 'The Lexra Story' and the MIPS-1 patent filing.

Thursday, January 10, 2019

Pylocky Unlocked: Cisco Talos releases PyLocky ransomware decryptor

This tool was developed by Mike Bautista.

PyLocky is a family of ransomware written in Python that attempts to masquerade as a Locky variant. This ransomware will encrypt all files on a victim machine before demanding that the user pay a ransom to gain access to their decrypted files. To combat this ransomware, Cisco Talos is releasing a free decryption tool. Because our tool requires the capturing of the initial PyLocky command and control (C2) traffic of an infected machine, it will only work to recover the files on an infected machine where network traffic has been monitored. If the initial C2 traffic has not been captured, our decryption tool will not be able to recover files on an infected machine. This is because the initial callout is used by the malware to send the C2 servers information that it uses in the encryption process.

Wednesday, January 9, 2019

Why we want users' feedback on Snort rule documentation

Today, Talos is launching a new community survey to solicit feedback on SNORTⓇ documentation.

When Snort alerts the end user, the rule documentation is their first and possibly only avenue to find information on malicious traffic in their network. We know this can be better, and we want your help in determining what we can do to make Snort users more knowledgable and provide them more information.

Tuesday, January 8, 2019

Microsoft Patch Tuesday — January 2019: Vulnerability disclosures and Snort coverage

Microsoft released its monthly security update today, disclosing a variety of vulnerabilities in several of its products. The latest Patch Tuesday covers 49 vulnerabilities, seven of which are rated “critical,” 40 that are considered “important” and one that is “moderate.” This release also includes a critical security advisory for multiple bugs in Adobe Flash Player.

This month’s security update covers security issues in a variety of Microsoft’s products, including the Jet Database Engine, Office SharePoint and the Chakra Scripting Engine. For coverage of these vulnerabilities, read the SNORTⓇ blog post here.