Today, Talos is publishing a glimpse into the most prevalent threats we've observed between March 6 and March 13. 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, Snort.org, or ClamAV.net.
For each threat described below, this blog post only lists 25 of the associated file hashes and up to 25 IOCs for each category. An accompanying JSON file can be found here that includes the complete list of file hashes, as well as all other IOCs from this post. As always, please remember that all IOCs contained in this document are indicators, and one single IOC does not indicate maliciousness. The most prevalent threats highlighted in this roundup are:
Nymaim is malware that can be used to deliver ransomware and other malicious payloads. It uses a domain generation algorithm to generate potential command and control (C2) domains to connect to additional payloads.
Ursu is a generic malware that has numerous functions. It contacts a C2 server and performs code injection in the address space of legitimate processes. It is able to achieve persistence and collect confidential data. It is spread via email.
Cerber is ransomware that encrypts documents, photos, databases and other important files. Historically, this malware would replace files with encrypted versions and add the file extension ".cerber," although in more recent campaigns, other file extensions are used.
Gandcrab is ransomware that encrypts documents, photos, databases and other important files using the file extension ".GDCB," ".CRAB" or ".KRAB". Gandcrab is spread through both traditional spam campaigns, as well as multiple exploit kits, including Rig and Grandsoft.
Indicators of Compromise
IOCs collected from dynamic analysis of 25 samples
Value Name: mbijg
Value Name: efp
Domain Names contacted by malware. Does not indicate maliciousness
Exploit Prevention Cisco AMP for Endpoints protects users from a variety of malware functions with exploit prevention. Exploit prevention helps users defend endpoints from memory attacks commonly used by obfuscated malware and exploits. These exploits use certain features to bypass typical anti-virus software, but were blocked by AMP thanks to its advanced scanning capabilities, even protecting against zero-day vulnerabilities.
CVE-2019-0708 detected - (4171)
An attempt to exploit CVE-2019-0708 has been detected. The vulnerability, dubbed BlueKeep, is a heap memory corruption which can be triggered by sending a specially crafted Remote Desktop Protocol (RDP) request. Since this vulnerability can be triggered without authentication and allows remote code execution, it can be used by worms to spread automatically without human interaction.
Excessively long PowerShell command detected - (1148)
A PowerShell command with a very long command line argument that may indicate an obfuscated script has been detected. PowerShell is an extensible Windows scripting language present on all versions of Windows. Malware authors use PowerShell in an attempt to evade security software or other monitoring that is not tuned to detect PowerShell based threats.
Dealply adware detected - (295)
DealPly is adware, which claims to improve your online shopping experience. It is often bundled into other legitimate installers and is difficult to uninstall. It creates pop-up advertisements and injects advertisements on webpages. Adware has also been known to download and install malware.
Process hollowing detected - (191)
Process hollowing is a technique used by some programs to avoid static analysis. In typical usage, a process is started and its obfuscated or encrypted contents are unpacked into memory. The parent then manually sets up the first stages of launching a child process, but before launching it, the memory is cleared and filled in with the memory from the parent instead.
Gamarue malware detected - (164)
Gamarue is a family of malware that can download files and steal information from an infected system. Worm variants of the Gamarue family may spread by infecting USB drives or portable hard disks that have been plugged into a compromised system.
Kovter injection detected - (122)
A process was injected into, most likely by an existing Kovter infection. Kovter is a click fraud Trojan that can also act as an information stealer. Kovter is also file-less malware meaning the malicious DLL is stored inside Windows registry and injected directly into memory using PowerShell. It can detect and report the usage of monitoring software such as wireshark and sandboxes to its C2. It spreads through malicious advertising and spam campaigns.
Installcore adware detected - (62)
Install core is an installer which bundles legitimate applications with offers for additional third-party applications that may be unwanted. The unwanted applications are often adware that display advertising in the form of popups or by injecting into browsers and adding or altering advertisements on webpages. Adware is known to sometimes download and install malware.
PowerShell file-less infection detected - (25)
A PowerShell command was stored in an environment variable and run. The environment variable is commonly set by a previously run script and is used as a means of evasion. This behavior is a known tactic of the Kovter and Poweliks malware families.
Reverse http payload detected - (20)
An exploit payload intended to connect back to an attacker controlled host using http has been detected.
Possible fileless malware download - (18)
A site commonly used by fileless malware to download additional data has been detected. Several different families of malware have been observed using these sites to download additional stages to inject into other processes.