CVE-2014-9050 (published 2014-12-01T15:59Z)

Heap-based buffer overflow in the cli_scanpe function in libclamav/pe.c in ClamAV before 0.98.5 allows remote attackers to cause a denial of service (crash) via a crafted y0da Crypter PE file.

Severity: MEDIUM
CVSS v2 base score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/vrtadmin/clamav-devel
commit_details: repo_url: https://github.com/vrtadmin/clamav-devel
author: Shawn Webb
author_date: 2014-11-06 14:44:53-05:00
msg: Merge fix from security/bb11155 branch
repository: repo_url: https://github.com/vrtadmin/clamav-devel
repo_name: Cisco-Talos/clamav
description: ClamAV - Documentation is here: https://docs.clamav.net
repo_language: C
owner: vrtadmin
file_changes: filename: pe.c
change_type: ModificationType.MODIFY
diff: @@ -737,14 +737,14 @@ int cli_scanpe(cli_ctx *ctx)
 	char sname[9], epbuff[4096], *tempfile;
 	uint32_t epsize;
 	ssize_t bytes, at;
-	unsigned int i, found, upx_success = 0, min = 0, max = 0, err, overlays = 0;
+	unsigned int i, j, found, upx_success = 0, min = 0, max = 0, err, overlays = 0, rescan = 1;
 	unsigned int ssize = 0, dsize = 0, dll = 0, pe_plus = 0, corrupted_cur;
 	int (*upxfn)(const char *, uint32_t, char *, uint32_t *, uint32_t, uint32_t, uint32_t) = NULL;
 	const char *src = NULL;
 	char *dest = NULL;
 	int ndesc, ret = CL_CLEAN, upack = 0, native=0;
 	size_t fsize;
-	uint32_t valign, falign, hdr_size, j;
+	uint32_t valign, falign, hdr_size;
 	struct cli_exe_section *exe_sections;
 	char timestr[32];
 	struct pe_image_data_dir *dirs;
@@ -1238,18 +1238,52 @@ int cli_scanpe(cli_ctx *ctx)
     cli_jsonint(pe_json, "NumberOfSections", nsections);
 #endif
 
+    while (rescan==1) {
+        rescan=0;
+        for (i=0; i < nsections; i++) {
+            exe_sections[i].rva = PEALIGN(EC32(section_hdr[i].VirtualAddress), valign);
+            exe_sections[i].vsz = PESALIGN(EC32(section_hdr[i].VirtualSize), valign);
+            exe_sections[i].raw = PEALIGN(EC32(section_hdr[i].PointerToRawData), falign);
+            exe_sections[i].rsz = PESALIGN(EC32(section_hdr[i].SizeOfRawData), falign);
+            exe_sections[i].chr = EC32(section_hdr[i].Characteristics);
+            exe_sections[i].urva = EC32(section_hdr[i].VirtualAddress); /* Just in case */
+            exe_sections[i].uvsz = EC32(section_hdr[i].VirtualSize);
+            exe_sections[i].uraw = EC32(section_hdr[i].PointerToRawData);
+            exe_sections[i].ursz = EC32(section_hdr[i].SizeOfRawData);
+
+            if (exe_sections[i].rsz) { /* Don't bother with virtual only sections */
+                if (!CLI_ISCONTAINED(0, fsize, exe_sections[i].uraw, exe_sections[i].ursz)
+                    || exe_sections[i].raw >= fsize) {
+                    cli_dbgmsg("Broken PE file - Section %d starts or exists beyond the end of file (Offset@ %lu, Total filesize %lu)\n", i, (unsigned long)exe_sections[i].raw, (unsigned long)fsize);
+                    if (nsections == 1) {
+                        free(section_hdr);
+                        free(exe_sections);
+
+                        if(DETECT_BROKEN_PE) {
+                            cli_append_virus(ctx, "Heuristics.Broken.Executable");
+                            return CL_VIRUS;
+                        }
+
+                        return CL_CLEAN; /* no ninjas to see here! move along! */
+                    }
+
+                    for (j=i; j < nsections-1; j++)
+                        memcpy(&exe_sections[j], &exe_sections[j+1], sizeof(struct cli_exe_section));
+
+                    for (j=i; j < nsections-1; j++)
+                        memcpy(&section_hdr[j], &section_hdr[j+1], sizeof(struct pe_image_section_hdr));
+
+                    nsections--;
+                    rescan=1;
+                    break;
+                }
+            }
+        }
+    }
+
     for(i = 0; i < nsections; i++) {
-	strncpy(sname, (char *) section_hdr[i].Name, 8);
-	sname[8] = 0;
-	exe_sections[i].rva = PEALIGN(EC32(section_hdr[i].VirtualAddress), valign);
-	exe_sections[i].vsz = PESALIGN(EC32(section_hdr[i].VirtualSize), valign);
-	exe_sections[i].raw = PEALIGN(EC32(section_hdr[i].PointerToRawData), falign);
-	exe_sections[i].rsz = PESALIGN(EC32(section_hdr[i].SizeOfRawData), falign);
-	exe_sections[i].chr = EC32(section_hdr[i].Characteristics);
-	exe_sections[i].urva = EC32(section_hdr[i].VirtualAddress); /* Just in case */
-	exe_sections[i].uvsz = EC32(section_hdr[i].VirtualSize);
-	exe_sections[i].uraw = EC32(section_hdr[i].PointerToRawData);
-	exe_sections[i].ursz = EC32(section_hdr[i].SizeOfRawData);
+        strncpy(sname, (char *) section_hdr[i].Name, 8);
+        sname[8] = 0;
 
 #if HAVE_JSON
         add_section_info(ctx, &exe_sections[i]);
@@ -1304,18 +1338,6 @@ int cli_scanpe(cli_ctx *ctx)
 	}
 
 	if (exe_sections[i].rsz) { /* Don't bother with virtual only sections */
-	    if (exe_sections[i].raw >= fsize) { /* really broken */
-	      cli_dbgmsg("Broken PE file - Section %d starts beyond the end of file (Offset@ %lu, Total filesize %lu)\n", i, (unsigned long)exe_sections[i].raw, (unsigned long)fsize);
-	      cli_dbgmsg("------------------------------------\n");
-		free(section_hdr);
-		free(exe_sections);
-		if(DETECT_BROKEN_PE) {
-		    cli_append_virus(ctx, "Heuristics.Broken.Executable");
-		    return CL_VIRUS;
-		}
-		return CL_CLEAN; /* no ninjas to see here! move along! */
-	    }
-
 	    if(SCAN_ALGO && (DCONF & PE_CONF_POLIPOS) && !*sname && exe_sections[i].vsz > 40000 && exe_sections[i].vsz < 70000 && exe_sections[i].chr == 0xe0000060) polipos = i;
 
 	    /* check hash section sigs */

programming_language: C