snap7 through 1.4.3 Out-of-Bounds Write via TSnap7MicroClient::opReadArea

snap7 through 1.4.3 contains an out-of-bounds write vulnerability in TSnap7MicroClient::opReadArea() that allows malicious S7 peers to overflow client buffers via an unchecked DataLength field. Rogue or impersonated PLCs can return crafted ReadVar responses causing memcpy of up to 65535 bytes into caller buffers, crashing SCADA, HMI, or gateway processes and corrupting memory.

Snap7 through 1.4.3 Out-of-Bounds Write via BRecv and CheckAsBRecvCompletion

Snap7 through 1.4.3 contains an out-of-bounds write vulnerability in the passive partner that allows a malicious active partner to overflow application buffers by declaring an unvalidated BSend total length. Attackers connecting from the configured peer address can declare up to 65535 bytes and send a short fragment, causing BRecv to memcpy past the buffer and crash or corrupt SCADA, HMI or gateway processes.

The Snap7 Server version 1.4.1 can be crashed when the ItemCount field of the ReadVar or WriteVar functions of the S7 protocol implementation in Snap7 are provided with unexpected input, thus resulting in denial of service attack.

The Snap7 server component in version 1.4.1, when an attacker sends a crafted packet with COTP protocol the last-data-unit flag set to No and S7 writes a var function, the Snap7 server will be crashed.