CVE-2019-5181: Buffer Overflow

An exploitable stack buffer overflow vulnerability vulnerability exists in the iocheckd service ‘I/O-Check’ functionality of WAGO PFC 200 Firmware version 03.02.02(14). A specially crafted XML cache file written to a specific location on the device can cause a stack buffer overflow, resulting in code execution. An attacker can send a specially crafted packet to trigger the parsing of this cache file. The destination buffer sp+0x440 is overflowed with the call to sprintf() for any subnetmask values that are greater than 1024-len(‘/etc/config-tools/configinterfaces interface=X1 state=enabled subnet-mask=‘) in length. A subnetmask value of length 0x3d9 will cause the service to crash.