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Multiple up-imapproxy DoS Vulnerabilities
------------------------------------------------------------------------
SUMMARY
<http://www.imapproxy.org/> up-imapproxy is "an IMAP proxy that keeps
connections open after client has logged out, and reuses it when client
connects back. This is mostly useful for webmail-type clients".
There are various bugs in up-imapproxy that can crash it. Since
up-imapproxy runs in a single process with each connection handled in a
separate thread, any crash kills all the connections and stops listening
for new ones. In 64bit systems it might be possible to make it leak data
(mails, passwords, ..) from other connections to attacker's connection.
DETAILS
Vulnerable Systems:
* up-imapproxy version 1.2.2
up-imapproxy's literal sizes are stored in a signed long integer. This
allows attacker to cause the server to crash by sending them when they
were not "expected". Such is the case in IMAP_Line_Read(), which allows
literals, but it's used in some places where literals weren't expected.
Any misuse will kill the proxy.
One example is user/password in AUTHENTICATE LOGIN. In addition if literal
is given to an unknown command, it's not properly handled. For example
issuing the following command "x foo {5}" will kill the proxy.
Workaround:
Don't give direct IMAP access to up-imapproxy. It shouldn't be possible to
exploit these bugs via webmails.
Fix:
Author seems to have gone away. Timo tried sending a few emails over a
month ago with no reply. Its web site is currently broken too.
Timo does not really like saying "no fix available", so he wrote a patch
which fixes the above problems. There might still be some problems left
though. Note that Timo did only minimal testing with the patch.
diff -ru up-imapproxy-1.2.2/include/imapproxy.h
up-imapproxy-1.2.2-fixed/include/imapproxy.h
--- up-imapproxy-1.2.2/include/imapproxy.h 2004-07-23 16:17:24.000000000
+0300
+++ up-imapproxy-1.2.2-fixed/include/imapproxy.h 2004-11-07
18:51:00.000000000 +0200
@@ -206,7 +206,7 @@
char ReadBuf[ BUFSIZE ]; /* Read Buffer */
unsigned int BytesInReadBuffer; /* bytes left in read buffer */
unsigned int ReadBytesProcessed; /* bytes already processed in read
buf */
- long LiteralBytesRemaining; /* num of bytes left to read as literal */
+ unsigned long LiteralBytesRemaining;/* num of bytes left to read as
literal */
unsigned char NonSyncLiteral; /* rfc2088 alert flag */
unsigned char MoreData; /* flag to tell caller "more data" */
unsigned char TraceOn; /* trace this transaction? */
@@ -304,7 +304,7 @@
*/
extern int IMAP_Write( ICD_Struct *, const void *, int );
extern int IMAP_Read( ICD_Struct *, void *, int );
-extern int IMAP_Line_Read( ITD_Struct * );
+extern int IMAP_Line_Read( ITD_Struct *, int );
extern int IMAP_Literal_Read( ITD_Struct * );
extern void HandleRequest( int );
extern char *memtok( char *, char *, char ** );
diff -ru up-imapproxy-1.2.2/src/imapcommon.c
up-imapproxy-1.2.2-fixed/src/imapcommon.c
--- up-imapproxy-1.2.2/src/imapcommon.c 2004-07-23 16:17:25.000000000
+0300
+++ up-imapproxy-1.2.2-fixed/src/imapcommon.c 2004-11-07
18:54:05.000000000 +0200
@@ -428,7 +428,7 @@
/* Read & throw away the banner line from the server */
- if ( IMAP_Line_Read( &Server ) == -1 )
+ if ( IMAP_Line_Read( &Server, 0 ) == -1 )
{
syslog(LOG_INFO, "LOGIN: '%s' (%s:%d) failed: No banner line
received from IMAP server", Username, ClientAddr, sin_port );
goto fail;
@@ -451,7 +451,7 @@
/*
* Read the server response
*/
- if ( ( rc = IMAP_Line_Read( &Server ) ) == -1 )
+ if ( ( rc = IMAP_Line_Read( &Server, 0 ) ) == -1 )
{
syslog(LOG_INFO, "STARTTLS failed: No response from IMAP
server after sending STARTTLS command" );
goto fail;
@@ -555,7 +555,7 @@
/*
* the server response should be a go ahead
*/
- if ( ( rc = IMAP_Line_Read( &Server ) ) == -1 )
+ if ( ( rc = IMAP_Line_Read( &Server, 0 ) ) == -1 )
{
syslog(LOG_INFO, "LOGIN: '%s' (%s:%d) failed: Failed to
receive go-ahead from IMAP server after sending LOGIN command", Username,
ClientAddr, sin_port );
goto fail;
@@ -611,7 +611,7 @@
*/
for ( ;; )
{
- if ( ( rc = IMAP_Line_Read( &Server ) ) == -1 )
+ if ( ( rc = IMAP_Line_Read( &Server, 0 ) ) == -1 )
{
syslog(LOG_INFO, "LOGIN: '%s' (%s:%d) failed: No response from
IMAP server after sending LOGIN command", Username, ClientAddr, sin_port
);
goto fail;
@@ -951,7 +951,8 @@
extern int IMAP_Literal_Read( ITD_Struct *ITD )
{
char *fn = "IMAP_Literal_Read()";
- int Status, i, j;
+ int Status;
+ unsigned int i, j;
struct pollfd fds[2];
nfds_t nfds;
int pollstatus;
@@ -1080,10 +1081,11 @@
* process.
*--
*/
-extern int IMAP_Line_Read( ITD_Struct *ITD )
+extern int IMAP_Line_Read( ITD_Struct *ITD, int useLiterals )
{
char *CP;
- int Status, i, j;
+ int Status;
+ unsigned int i, j;
char *fn = "IMAP_Line_Read()";
char *EndOfBuffer;
@@ -1152,7 +1154,8 @@
* string literal is coming next. How do we know?
* If it is, the line will end with {bytecount}.
*/
- if ( ((CP - ITD->ReadBuf + 1) > 2 ) && ( *(CP - 2) == '}' ))
+ if ( ((CP - ITD->ReadBuf + 1) > 2 ) && ( *(CP - 2) == '}' )
+ && useLiterals)
{
char *LiteralEnd;
char *LiteralStart;
diff -ru up-imapproxy-1.2.2/src/main.c up-imapproxy-1.2.2-fixed/src/main.c
--- up-imapproxy-1.2.2/src/main.c 2004-07-23 16:17:25.000000000 +0300
+++ up-imapproxy-1.2.2-fixed/src/main.c 2004-11-07 18:52:41.000000000
+0200
@@ -931,7 +931,7 @@
* The first thing we get back from the server should be the
* banner string.
*/
- BytesRead = IMAP_Line_Read( &itd );
+ BytesRead = IMAP_Line_Read( &itd, 0 );
if ( BytesRead == -1 )
{
syslog( LOG_ERR, "%s: Error reading banner line from server on
initial connection: %s -- Exiting.", fn, strerror( errno ) );
@@ -973,7 +973,7 @@
* The second will be the OK response with the tag in it.
*/
- BytesRead = IMAP_Line_Read( &itd );
+ BytesRead = IMAP_Line_Read( &itd, 0 );
if ( BytesRead == -1 )
{
syslog( LOG_ERR, "%s: Failed to read capability response from
server: %s -- exiting.", fn, strerror( errno ) );
@@ -986,7 +986,7 @@
/* Now read the tagged response and make sure it's OK */
- BytesRead = IMAP_Line_Read( &itd );
+ BytesRead = IMAP_Line_Read( &itd, 0 );
if ( BytesRead == -1 )
{
syslog( LOG_ERR, "%s: Failed to read capability response from
server: %s -- exiting.", fn, strerror( errno ) );
@@ -1011,7 +1011,7 @@
}
/* read the final OK logout */
- BytesRead = IMAP_Line_Read( &itd );
+ BytesRead = IMAP_Line_Read( &itd, 0 );
if ( BytesRead == -1 )
{
syslog(LOG_WARNING, "%s: IMAP_Line_Read() failed on LOGOUT --
Ignoring", fn );
diff -ru up-imapproxy-1.2.2/src/request.c
up-imapproxy-1.2.2-fixed/src/request.c
--- up-imapproxy-1.2.2/src/request.c 2004-07-23 16:17:26.000000000 +0300
+++ up-imapproxy-1.2.2-fixed/src/request.c 2004-11-07 19:05:09.000000000
+0200
@@ -433,6 +433,7 @@
}
strncpy( TraceUser, Username, sizeof TraceUser - 1 );
+ TraceUser[sizeof TraceUser - 1] = '\0';
snprintf( SendBuf, BufLen, "%s OK Tracing enabled\r\n", Tag );
if ( IMAP_Write( itd->conn, SendBuf, strlen(SendBuf) ) == -1 )
@@ -611,7 +612,7 @@
* The response from the client should be a base64 encoded version of
the
* username.
*/
- BytesRead = IMAP_Line_Read( Client );
+ BytesRead = IMAP_Line_Read( Client, 0 );
if ( BytesRead == -1 )
{
@@ -654,7 +655,7 @@
return( -1 );
}
- BytesRead = IMAP_Line_Read( Client );
+ BytesRead = IMAP_Line_Read( Client, 0 );
if ( BytesRead == -1 )
{
@@ -1097,7 +1098,7 @@
{
do
{
- status = IMAP_Line_Read( Client );
+ status = IMAP_Line_Read( Client, 1 );
if ( status == -1 )
{
@@ -1152,7 +1153,7 @@
if ( Server->LiteralBytesRemaining )
break;
- status = IMAP_Line_Read( Server );
+ status = IMAP_Line_Read( Server, 1 );
/*
* If there's an error reading from the
server,
@@ -1266,7 +1267,7 @@
if ( ! Client->NonSyncLiteral )
{
/* we have to wait for a go-ahead */
- status = IMAP_Line_Read( Server );
+ status = IMAP_Line_Read( Server, 0 );
if ( Server->TraceOn )
{
snprintf( TraceBuf, sizeof TraceBuf - 1, "\n\n----->
C= %d %s SERVER: sd [%d]\n", time( 0 ), ( (TraceUser) ? TraceUser : "Null
username" ), Server->conn->sd );
@@ -1473,7 +1474,19 @@
PollFailCount = 0;
- BytesRead = IMAP_Line_Read( &Client );
+ while ( Client.LiteralBytesRemaining )
+ {
+ BytesRead = IMAP_Literal_Read( &Client );
+
+ if ( BytesRead == -1 )
+ {
+ IMAPCount->CurrentClientConnections--;
+ close( Client.conn->sd );
+ return;
+ }
+ }
+
+ BytesRead = IMAP_Line_Read( &Client, 1 );
if ( BytesRead == -1 )
{
@@ -1530,6 +1543,7 @@
* appropriate...
*/
strncpy( S_Tag, Tag, MAXTAGLEN - 1 );
+ S_Tag[MAXTAGLEN - 1] = '\0';
if ( ! strcasecmp( (const char *)Command, "NOOP" ) )
{
cmd_noop( &Client, S_Tag );
@@ -1569,6 +1583,7 @@
if ( Tag )
{
strncpy( S_Tag, Tag, MAXTAGLEN - 1 );
+ S_Tag[MAXTAGLEN - 1] = '\0';
cmd_logout( &Client, S_Tag );
}
}
@@ -1641,7 +1656,8 @@
}
continue;
}
- strncpy( S_UserName, Username, sizeof S_UserName - 1 );
+ strncpy( S_UserName, Username, sizeof S_UserName - 1 );
+ S_UserName[sizeof S_UserName - 1] = '\0';
/*
* Clients can send the password as a literal bytestream.
Check
@@ -1720,7 +1736,7 @@
* IMAP_Literal_Read() right now since it works properly
* otherwise.
*/
- rc = IMAP_Line_Read( &Client );
+ rc = IMAP_Line_Read( &Client, 1 );
}
else
{
@@ -1748,6 +1764,7 @@
*CP = '\0';
strncpy( S_Password, Lasts, sizeof S_Password - 1 );
+ S_Password[sizeof S_Password - 1] = '\0';
}
@@ -1779,6 +1796,7 @@
if ( Tag )
{
strncpy( S_Tag, Tag, MAXTAGLEN - 1 );
+ S_Tag[MAXTAGLEN - 1] = '\0';
cmd_logout( &Client, S_Tag );
}
}
diff -ru up-imapproxy-1.2.2/src/select.c
up-imapproxy-1.2.2-fixed/src/select.c
--- up-imapproxy-1.2.2/src/select.c 2004-07-23 16:17:25.000000000 +0300
+++ up-imapproxy-1.2.2-fixed/src/select.c 2004-11-07 18:56:01.000000000
+0200
@@ -356,7 +356,7 @@
return( -1 );
}
- rc = IMAP_Line_Read( Server );
+ rc = IMAP_Line_Read( Server, 0 );
if ( ( rc == -1 ) || ( rc == 0 ) )
{
@@ -417,6 +417,7 @@
ISC->ISCTime = time( 0 );
strncpy( (char *)ISC->MailboxName, (const char *)MailboxName,
MAXMAILBOXNAME - 1 );
+ ISC->MailboxName[MAXMAILBOXNAME - 1] = '\0';
return( 0 );
ADDITIONAL INFORMATION
The information has been provided by <mailto:tss@iki.fi> Timo Sirainen.
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