Cisco Threat Research Blog

Vulnerability Discovered by Cory Duplantis of Cisco Talos

Overview

Talos is disclosing TALOS-2016-0227 / CVE-2016-8714 which is a buffer overflow vulnerability in the LoadEncoding functionality of the R programming language version 3.3.0. The R programming language is commonly used in statistical computing and is supported by the R Foundation for Statistical Computing. R is praised for having a large variety of statistical and graphical features. The vulnerability is specifically related to the creation of a PDF document.

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This Post Authored by Nick Biasini

UPDATE: It was recently disclosed that in addition to Content-Type being vulnerable, both Content-Disposition and Content-Length can be manipulated to trigger this particular vulnerability. No new CVE was listed, however details of the vulnerability and remediation are available in this security advisory.

Talos has observed a new Apache vulnerability that is being actively exploited in the wild. The vulnerability (CVE-2017-5638) is a remote code execution bug that affects the Jakarta Multipart parser in Apache Struts, referenced in this security advisory. Talos began investigating for exploitation attempts and found a high number of exploitation events. The majority of the exploitation attempts seem to be leveraging a publicly released PoC that is being used to run various commands. Talos has observed simple commands (i.e. whoami) as well as more sophisticated commands including pulling down a malicious ELF executable and execution.

With exploitation actively underway Talos recommends immediate upgrading if possible or following the work around referenced in the above security advisory.

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Ransomware continues to be a plague on the internet and still sets itself as the fastest growing malware family we have seen in the last number of years. In this post we describe the technical details about a newly observed campaign of the notorious Crypt0l0cker (aka TorrentLocker or Teerac) ransomware. Crypt0l0cker has gone through a long evolution, the adversaries are updating and improving the malware on a regular basis. Several indicators inside the samples we have analysed point to a new major version of the malware. We have already seen large campaigns targeting Europe and other parts of the world in 2014 and 2015. It seems to be that the actors behind these campaigns are back now and launching again massive spam attacks. This post will also give you insights about the level of sophistication this malware has reached.

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This post was authored by Edmund Brumaghin and Colin Grady

Executive Summary

The Domain Name System (DNS) is one of the most commonly used Internet application protocols on corporate networks. It is responsible for providing name resolution so that network resources can be accessed by name, rather than requiring users to memorize IP addresses. While many organizations implement strict egress filtering as it pertains to web traffic, firewall rules, etc. many have less stringent controls in place to protect against DNS based threats. Attackers have recognized this and commonly encapsulate different network protocols within DNS to evade security devices.

Typically this use of DNS is related to the exfiltration of information. Talos recently analyzed an interesting malware sample that made use of DNS TXT record queries and responses to create a bidirectional Command and Control (C2) channel. This allows the attacker to use DNS communications to submit new commands to be run on infected machines and return the results of the command execution to the attacker. This is an extremely uncommon and evasive way of administering a RAT. The use of multiple stages of Powershell with various stages being completely fileless indicates an attacker who has taken significant measures to avoid detection.

Ironically, the author of the malware called SourceFire out in the malware code itself shortly after we released Cisco Umbrella, a security product specifically designed to protect organizations from DNS and web based threats as described here.

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Summary

Talos has become aware of active scanning against customer infrastructure with the intent of finding Cisco Smart Install clients. Cisco Smart Install is one component of the Cisco Smart Operations solution that facilitates the management of LAN switches. Research has indicated that malicious actors may be leveraging detailed knowledge of the Smart Install Protocol to obtain copies of customer configurations from affected devices. The attack leverages a known issue with the Smart Install protocol. Cisco PSIRT has published a security response to this activity. Abuse of the Smart Install protocol can lead to modification of the TFTP server setting, exfiltration of configuration files via TFTP, replacement of IOS image and potentially execution of IOS commands.

We are aware that a tool to scan for affected systems, called the Smart Install Exploitation Tool (SIET), has been publicly released and is available here. This tool may be being used in these attacks.

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Overview

Talos has discovered multiple vulnerabilities in Iceni Argus PDF content extraction product. Exploiting these vulnerabilities can allow an attacker to gain full control over the victim’s machine. Although the main product is deprecated by Iceni, the library is still supported. Iceni has released a patched version that addresses these vulnerabilities. Nevertheless, the library is widely used; MarkLogic is an example of a product that uses Iceni Argus for PDF document conversion as part of their web based document search and rendering.

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