Supply chain attacks are a very effective way to distribute malicious software into target organizations. This is because with supply chain attacks, the attackers are relying on the trust relationship between a manufacturer or supplier and a customer. This trust relationship is then abused to attack organizations and individuals and may be performed for a number of different reasons. The Nyetya worm that was released into the wild earlier in 2017 showed just how potent these types of attacks can be. Frequently, as with Nyetya, the initial infection vector can remain elusive for quite some time. Luckily with tools like AMP the additional visibility can usually help direct attention to the initial vector.
Talos recently observed a case where the download servers used by software vendor to distribute a legitimate software package were leveraged to deliver malware to unsuspecting victims. For a period of time, the legitimate signed version of CCleaner 5.33 being distributed by Avast also contained a multi-stage malware payload that rode on top of the installation of CCleaner. CCleaner boasted over 2 billion total downloads by November of 2016 with a growth rate of 5 million additional users per week. Given the potential damage that could be caused by a network of infected computers even a tiny fraction of this size we decided to move quickly. On September 13, 2017 Cisco Talos immediately notified Avast of our findings so that they could initiate appropriate response activities. The following sections will discuss the specific details regarding this attack.
Today, Talos is publishing a glimpse into the most prevalent threats we’ve observed between September 08 and September 15. As with previous round-ups, this post isn’t meant to be an in-depth analysis. Instead, this post will summarize the threats we’ve observed by highlighting key behavior characteristics, indicators of compromise, and 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 date of publication. 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, Snort.org, or ClamAV.net.
This post authored by Marcin Noga with contributions from William Largent
Talos discovers and responsibly discloses software vulnerabilities on a regular basis. Occasionally we publish a deep technical analysis of how the vulnerability was discovered or its potential impact. In a previous post Talos took a deep dive into Lexmark Perceptive Document Filters, in this post we are going to focus on another converter used by MarkLogic located in `Converters/cvtpdf` folder, which is responsible for converting pdf to XML-based formats – Argus PDF. This blog will cover the technical aspects including discovery and exploitation process via the Argus PDF converter.
Vulnerability Spotlight: YAML Parsing Remote Code Execution Vulnerabilities in Ansible Vault and Tablib.
Talos is disclosing the presences of remote code execution vulnerabilities in the processing of Yet Another Markup Language (YAML) content in Ansible Vault and Tablib. Attackers can exploit these vulnerabilities through supplying malicious YAML content to execute arbitrary commands on vulnerable systems.
YAML is a data serialisation markup format which is designed to be readable for humans yet easily parsed by machines. Many tools and libraries have been developed to parse YAML data. The Python YAML parsing library PyYAML provides two API calls to parse YAML data: yaml.load and yaml.safe_load. The former API does not correctly sanitise YAML input which allows attackers to embed Python code to be executed within YAML content.
This vulnerability was discovered by Cory Duplantis of Talos
Update 9/20/2017: A patch is now available to fix this issue.
LibOFX is an open source implementation of OFX (Open Financial Exchange) an open format used by financial institutions to share financial data with clients. As an implementation of a complex standard, this library is used by financial software such as GnuCash. Talos has discovered an exploitable buffer overflow in the implementation: a specially crafted OFX file can cause a write out of bounds resulting in code execution. This vulnerability is not currently patched and Talos has not received a response from the developers within the period specified by the Vendor Vulnerability Reporting and Disclosure Policy.
Microsoft has released its monthly set of security advisories for vulnerabilities that have been identified and addressed in various products. This month’s advisory release addresses 81 new vulnerabilities with 27 of them rated critical, 52 rated important, and 2 rated moderate. These vulnerabilities impact Edge, Hyper-V, Internet Explorer, Office, Remote Desktop Protocol, Sharepoint, Windows Graphic Display Interface, Windows Kernel Mode Drivers, and more. In addition, Microsoft is also releasing an update for Adobe Flash Player embedded in Edge and Internet Explorer.
Note that the Bluetooth vulnerabilities known as “BlueBorne” that affected Windows have been patched in this latest release. For more information, please refer to CVE-2017-8628.