Headline
CVE-2020-15137: Build software better, together
All versions of HoRNDIS are affected by an integer overflow in the RNDIS packet parsing routines. A malicious USB device can trigger disclosure of unrelated kernel memory to userspace applications on the host, or can cause the kernel to crash. Kernel memory disclosure is especially likely on 32-bit kernels; 64-bit kernels are more likely to crash on attempted exploitation. It is not believed that kernel memory corruption is possible, or that unattended kernel memory disclosure without the collaboration of a userspace program running on the host is possible. The vulnerability is in HoRNDIS::receivePacket. msg_len, data_ofs, and data_len can be controlled by an attached USB device, and a negative value of data_ofs can bypass the check for (data_ofs + data_len + 8) > msg_len, and subsequently can cause a wild pointer copy in the mbuf_copyback call. The software is not maintained and no patches are planned. Users of multi-tenant systems with HoRNDIS installed should only connect trusted USB devices to their system.
Impact
An integer overflow in the RNDIS packet parsing routines has been discovered, in which a malicious USB device can trigger disclosure of unrelated kernel memory to userspace applications on the host, or can cause the kernel to crash. Kernel memory disclosure is especially likely on 32-bit kernels; 64-bit kernels are more likely to crash on attempted exploitation. It is not believed that kernel memory corruption is possible, or that unattended kernel memory disclosure without the collaboration of a userspace program running on the host is possible.
Details
The vulnerability is in HoRNDIS::receivePacket. msg_len, data_ofs, and data_len can be controlled by an attached USB device, and a negative value of data_ofs can bypass the check for (data_ofs + data_len + 8) > msg_len, and subsequently can cause a wild pointer copy in the mbuf_copyback call.
Patches
This vulnerability currently does not have a patch. Because HoRNDIS is currently unmaintained, no fix is planned.
Workarounds
Users of multi-tenant systems with HoRNDIS installed should only connect trusted USB devices to their system.
Credits
This vulnerability was discovered by swing and chennan of the Chaitin Security Research Lab.