A cybercrime gang known as Gold Lowell has been using scan-and-exploit tactics to opportunistically infect business networks with ransomware and extort money from the victim organizations.
The group - which has been around since at least 2015 - appears to have ramped up activity in the last few weeks in keeping with its previous pattern of escalating attacks during the end part through the beginning of the calendar year, Secureworks said in a report this week.
Between late December and mid-January alone, Gold Lowell managed to collect at least $350,000 in extortion money after infecting victims with a custom version of SamSam, a previously known ransomware tool. The group's victims include healthcare organizations, IT software providers, transportation companies, waste management firms, and business services organizations. Many of them have been small- to midsized organizations.
From a malware perspective itself, SamSam is little different from the slew of ransomware tools floating about in the wild currently. The tactic Gold Lowell has been using to install the malware on victim systems and networks is notable, however, notes Matthew Webster, senior security researcher at Secureworks’ Counter Threat Unit.
"SamSam ransomware is essentially as sophisticated as it needs to be," Webster says. "The main contrast between other ransomware capabilities is how it is deployed—after compromise of the victim’s systems and account credentials."
According to Secureworks, Gold Lowell has shown a tendency to scan Internet-facing systems for known vulnerabilities and exploits. The group's scanning has targeted systems and protocols like JBoss and RDP that are more likely to be used by organizations than by individuals. Early on, the threat group regularly targeted JBoss applications using an open source exploitation tool. In 2017, Gold Lowell began targeting legitimate Remote Desktop Protocol (RDP) account credentials—often via brute force attacks, Secureworks said.
Once it gains at initial foothold on a network, Gold Lowell has shown a tendency to use both publicly available and proprietary tools and exploits in order to escalate privileges and find the most central and critical systems to exploit.
"[SamSam's] encryption methodology is strong and it carries out actions that make it more difficult for recovery and investigation," Webster says. Measures include wiping additional space on the disk and deleting itself, he says.
Gold Lowell typically demands a ransom of around $9,500 for decrypting files. But based on how effective the group has been at deploying SamSam inside breached networks, it is quite likely that some victims are paying up a lot more, according to Webster. In one campaign during mid-2017 that Secureworks researchers observed, the value of the ransom for decrypting the entire network of the victim organization was 28 bitcoins, or approximately $68,000 at the time, he says.
In at least one instance the threat actors doubled the decryption cost after a victim's initial payment barely missed the deadline set for it. "The doubling of the ransom really goes to highlight that once the decision has been made to pay the ransom, then as victim you are handing control over to the adversary," Webster says. Such incidents highlight the importance for organizations to have a well-tested data backup and incident response process in place, he notes.
Gold Lowell, however, generally takes steps to instill confidence that the victim will get their data back once payment has been received. It offers to decrypt files as a test, for instance, and advice on purchasing bitcoin and how to set up bitcoin wallet.
"Long-term ransomware campaigns only work if the victim is confident that they will get their data back, and the SamSam actors clearly take steps to instill that confidence," Webster says.
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