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smb: handles records with trailing nbss data

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If a file (read/write) SMB record has padding/trailing data
after the buffer being read or written, and that Suricata falls
in one case where it skips the data, it should skip until
the very end of the NBSS record, meaning it should also skip the
padding/trailing data.

Otherwise, an attacker may smuggle some NBSS/SMB record in this
trailing data, that will be interpreted by Suricata, but not
by the SMB client/server, leading to evasions.

Ticket: #5786
pull/8536/head
Philippe Antoine 3 years ago committed by Victor Julien
parent c1b7befb18
commit 233ab11148
3 changed files with 22 additions and 23 deletions
Show Stats Download Patch File Download Diff File

7
rust/src/smb/smb.rs
Unescape Escape View File

@ -1172,13 +1172,12 @@ impl SMBState {
}
}
pub fn set_skip(&mut self, direction: Direction, rec_size: u32, data_size: u32)
pub fn set_skip(&mut self, direction: Direction, nbss_remaining: u32)
{
let skip = rec_size.saturating_sub(data_size);
if direction == Direction::ToServer {
self.skip_ts = skip;
self.skip_ts = nbss_remaining;
} else {
self.skip_tc = skip;
self.skip_tc = nbss_remaining;
}
}

6
rust/src/smb/smb1.rs
Unescape Escape View File

@ -950,7 +950,7 @@ pub fn smb1_write_request_record(state: &mut SMBState, r: &SmbRecord, andx_offse
// Record claims more bytes than are in NBSS record...
state.set_event(SMBEvent::WriteRequestTooLarge);
// Skip the remaining bytes of the record.
state.set_skip(Direction::ToServer, nbss_remaining, 0);
state.set_skip(Direction::ToServer, nbss_remaining);
return;
}
let mut file_fid = rd.fid.to_vec();
@ -1037,7 +1037,7 @@ pub fn smb1_read_response_record(state: &mut SMBState, r: &SmbRecord, andx_offse
// Record claims more bytes than are in NBSS record...
state.set_event(SMBEvent::ReadResponseTooLarge);
// Skip the remaining bytes of the record.
state.set_skip(Direction::ToClient, nbss_remaining, 0);
state.set_skip(Direction::ToClient, nbss_remaining);
return;
}
let fid_key = SMBCommonHdr::from1(r, SMBHDR_TYPE_OFFSET);
@ -1046,7 +1046,7 @@ pub fn smb1_read_response_record(state: &mut SMBState, r: &SmbRecord, andx_offse
None => {
SCLogDebug!("SMBv1 READ response: reply to unknown request: left {} {:?}",
rd.len - rd.data.len() as u32, rd);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
return;
},
};

32
rust/src/smb/smb2.rs
Unescape Escape View File

@ -126,7 +126,7 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
// Record claims more bytes than are in NBSS record...
state.set_event(SMBEvent::ReadResponseTooLarge);
// Skip the remaining bytes of the record.
state.set_skip(Direction::ToClient, nbss_remaining, 0);
state.set_skip(Direction::ToClient, nbss_remaining);
return;
}
if r.nt_status == SMB_NTSTATUS_BUFFER_OVERFLOW {
@ -135,7 +135,7 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
} else if r.nt_status != SMB_NTSTATUS_SUCCESS {
SCLogDebug!("SMBv2: read response error code received: skip record");
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
return;
}
@ -143,7 +143,7 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
(unsafe { SMB_CFG_MAX_READ_SIZE != 0 && SMB_CFG_MAX_READ_SIZE < rd.len })
{
state.set_event(SMBEvent::ReadResponseTooLarge);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
return;
}
@ -156,7 +156,7 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
Some(o) => (o.offset, o.guid),
None => {
SCLogDebug!("SMBv2 READ response: reply to unknown request {:?}",rd);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
return;
},
};
@ -173,10 +173,10 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
}
if max_queue_size != 0 && tdf.file_tracker.get_inflight_size() + rd.len as u64 > max_queue_size.into() {
state.set_event(SMBEvent::ReadQueueSizeExceeded);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
} else if max_queue_cnt != 0 && tdf.file_tracker.get_inflight_cnt() >= max_queue_cnt as usize {
state.set_event(SMBEvent::ReadQueueCntExceeded);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
} else {
filetracker_newchunk(&mut tdf.file_tracker,
&tdf.file_name, rd.data, offset,
@ -227,7 +227,7 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
smb_read_dcerpc_record(state, vercmd, hdr, &file_guid, rd.data);
} else if is_pipe {
SCLogDebug!("non-DCERPC pipe");
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
} else {
let file_name = match state.guid2name_map.get(&file_guid) {
Some(n) => { n.to_vec() }
@ -246,10 +246,10 @@ pub fn smb2_read_response_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
}
if max_queue_size != 0 && tdf.file_tracker.get_inflight_size() + rd.len as u64 > max_queue_size.into() {
state.set_event(SMBEvent::ReadQueueSizeExceeded);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
} else if max_queue_cnt != 0 && tdf.file_tracker.get_inflight_cnt() >= max_queue_cnt as usize {
state.set_event(SMBEvent::ReadQueueCntExceeded);
state.set_skip(Direction::ToClient, rd.len, rd.data.len() as u32);
state.set_skip(Direction::ToClient, nbss_remaining);
} else {
filetracker_newchunk(&mut tdf.file_tracker,
&file_name, rd.data, offset,
@ -288,13 +288,13 @@ pub fn smb2_write_request_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
// Record claims more bytes than are in NBSS record...
state.set_event(SMBEvent::WriteRequestTooLarge);
// Skip the remaining bytes of the record.
state.set_skip(Direction::ToServer, nbss_remaining, 0);
state.set_skip(Direction::ToServer, nbss_remaining);
return;
}
if (state.max_write_size != 0 && wr.wr_len > state.max_write_size) ||
(unsafe { SMB_CFG_MAX_WRITE_SIZE != 0 && SMB_CFG_MAX_WRITE_SIZE < wr.wr_len }) {
state.set_event(SMBEvent::WriteRequestTooLarge);
state.set_skip(Direction::ToServer, wr.wr_len, wr.data.len() as u32);
state.set_skip(Direction::ToServer, nbss_remaining);
return;
}
@ -318,10 +318,10 @@ pub fn smb2_write_request_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
}
if max_queue_size != 0 && tdf.file_tracker.get_inflight_size() + wr.wr_len as u64 > max_queue_size.into() {
state.set_event(SMBEvent::WriteQueueSizeExceeded);
state.set_skip(Direction::ToServer, wr.wr_len, wr.data.len() as u32);
state.set_skip(Direction::ToServer, nbss_remaining);
} else if max_queue_cnt != 0 && tdf.file_tracker.get_inflight_cnt() >= max_queue_cnt as usize {
state.set_event(SMBEvent::WriteQueueCntExceeded);
state.set_skip(Direction::ToServer, wr.wr_len, wr.data.len() as u32);
state.set_skip(Direction::ToServer, nbss_remaining);
} else {
filetracker_newchunk(&mut tdf.file_tracker,
&file_name, wr.data, wr.wr_offset,
@ -372,7 +372,7 @@ pub fn smb2_write_request_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
smb_write_dcerpc_record(state, vercmd, hdr, wr.data);
} else if is_pipe {
SCLogDebug!("non-DCERPC pipe: skip rest of the record");
state.set_skip(Direction::ToServer, wr.wr_len, wr.data.len() as u32);
state.set_skip(Direction::ToServer, nbss_remaining);
} else {
let tx = state.new_file_tx(&file_guid, &file_name, Direction::ToServer);
tx.vercmd.set_smb2_cmd(SMB2_COMMAND_WRITE);
@ -386,10 +386,10 @@ pub fn smb2_write_request_record(state: &mut SMBState, r: &Smb2Record, nbss_rema
if max_queue_size != 0 && tdf.file_tracker.get_inflight_size() + wr.wr_len as u64 > max_queue_size.into() {
state.set_event(SMBEvent::WriteQueueSizeExceeded);
state.set_skip(Direction::ToServer, wr.wr_len, wr.data.len() as u32);
state.set_skip(Direction::ToServer, nbss_remaining);
} else if max_queue_cnt != 0 && tdf.file_tracker.get_inflight_cnt() >= max_queue_cnt as usize {
state.set_event(SMBEvent::WriteQueueCntExceeded);
state.set_skip(Direction::ToServer, wr.wr_len, wr.data.len() as u32);
state.set_skip(Direction::ToServer, nbss_remaining);
} else {
filetracker_newchunk(&mut tdf.file_tracker,
&file_name, wr.data, wr.wr_offset,

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